Claudia Calleja
Channelling rainwater into boreholes
Marco Cremona has devised several water-saving measures.
Boreholes, that are mostly to blame for the over-extraction of Malta’s groundwater, may offer the solution to replenishing the precious resource – by pumping rainwater into them.
Hydrologist and environmental entrepreneur Marco Cremona is suggesting channelling rainwater that falls on roofs into shallow boreholes from where water would dissipate into the ground.
“Run-off generated from rainfall on roofs is generally clean, and may only contain some silt or particles from traffic and maybe some bacteria from bird droppings,” Mr Cremona told The Sunday Times.
“Practically all buildings in Malta are guttered and the rainwater is collected and channelled somewhere. In cases where there is no cistern it is channelled into the sewage system or the street.”
His aim is to throw his idea into the public domain so that the authorities would pick it up and drive it forward.
Experts have warned that Malta’s groundwater resources are running out and may vanish within the next five to 15 years. According to the European Commission, the free use of groundwater must stop before the end of the year or Malta may face legal action.
Meanwhile, the government has started a borehole registration process in an attempt to curb abuse.
Mr Cremona, who had devised an award-winning project to treat and recycle wastewater from a hotel, is determined to see his latest proposal discussed.
“Implementing this solution for 15 per cent of Malta’s built up area will avert 20 million cubic metres of flood water and enhance groundwater recharge by a substantial 50 per cent,” he said, adding it would also help keep water prices affordable.
He underlined the need to further develop the idea, particularly with regard to determining the optimum depth of the borehole for different geological situations.
Explaining the rationale behind his suggestion, Mr Cremona pointed out that during last Monday’s storm, Malta was showered with about 27 million litres of rainwater. Last year, the Water Services Corporation extracted 12.7 million litres of groundwater for distribution as tap water.
Although it is impossible to collect every drop, Mr Cremona is convinced some of it may be saved.
About 30 per cent of Malta’s surface area is built and most is made up of roofs equipped with rainwater collection systems that channel water into cisterns, the sewage system, or into the street.
Given the fact that a law stating all houses should be equipped with cisterns or wells has been ignored for years, most of the water goes to waste.
To make matters worse, when large amounts of water gush into the sewage system it results in sewage outpours that contaminate the water in the streets.
Therefore, the ideal place to collect water is “upstream” rather than gathering it after it travels through roads and becomes contaminated, he said.
Since retro-fitting cisterns in buildings are practically impossible, this is where his idea fits in – to channel rainwater into the ground through boreholes.
The drilling of boreholes, to be financed by tenants, should be carried out by the WSC or licensed contractors who will ensure the borehole is sealed off and tamper-proof. Mr Cremona said sceptics may try to kill off the idea by saying it poses a threat to the quality for the groundwater.
“I counter this argument by saying: what’s preventing contaminated run-off (water) from infiltrating valleys lined with toxic rubbish from reaching the aquifers all around Malta?... What about the huge leakages from our sewage system?”
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29 Comments
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Joe Diacono
Jul 15th 2011, 09:23
Whilst agreeing totally with Marco Cremona's comments one can also include those underground shelters full to the brim with water.
I know that in Sliema water is siphoned out to water the various trees in Sliema; this however covers only a fraction of the water available for use.
Much more use can be made of this water, and this could be an idea well worth implementing.
The same can be said for Valletta, Floriana, Mdina and Rabat too.
Water is a precious resource and more media attention will help to drive the point home.
Another point is that of ensuring that the water collected from roofs in apartment blocks being built is stored, pumped up into a common tank and used for the flushing of toilets, this instead of letting it run off into the sea.
Our forefathers where wise on how to store this precious resource,we have a lot of lessons to learn from their wisdom.
.
j.saliba
Nov 1st 2010, 09:28
It is too early to judge. The idea is simple - a characteristic of the great. 'Prima facie' it deserves consideration. Studies should be carried out in order to establish its feasability and establishent. This is not a populist idea. Experts and the country's interest should decide. Still I classify Marco Cremona's idea as great and orignal. I augur it to become practical and beneficial.
Christian Sciberras
Nov 1st 2010, 02:10
Marco, though I award you the idea of a profitable solution, I believe Malta is not in a place to fix the issue.
One should fix the issue, by proper draining, and only then perfect the system by perhaps load-balancing into bore holes.
Sadly, there's no such way one can do this in Malta....what with MEPA at your throat and investors only interested in the highest bidder (ie, igaming)...
Marco Cremona
Nov 1st 2010, 08:33
Christian, cannot clearly understand your post.
Malta has the highest water competitivity index in the world i.e. the least amount of renewable water per capita, and there is no doubt that the source of 2/3 of our water today i.e. the groundwater resource is diminishing year after year.
Moreover, we have no flood mitigation infrastructure to talk of, and channelling runoff directly into the sea and not recovering a substantial amount of rainfall which causes the same floods is a very short-sighted view.
So we need these kind of solutions more than anybody else. Please elaborate on your argument.
Mario Bianchin
Oct 31st 2010, 19:43
Thank you Marco for keeping the issue of groundwater preservation in the public eye. Yes, this article provides a simple solution to the negative groundwater balance in most of Malta's aquifers. Yet, I don't view it is as a pragmatic solution to this crisis for some of the good points mentioned, in particular, the control of the quality of recharge waters (which is a task in itself considering the physiography of Malta and the anthropogenic signature on it). I appreciate the input from all comments...it is a good exchange of conversation...including comments from John Mangion placing this article in the context of current legislation. This is what is truly valuable here, this message of dialogue. I view the challenges of reaching sustainable yield and 'acceptable' water quality status in Malta's aquifers as being more sociopolitical than technical. The solution will lie, hopefully, somewhere in a 'dynamic' balance between economic, political, social and environmental realms. This can only come about through increased dialogue, initiated by expression of concern like that by Marco today but, also by government being more outward and transparent in its planning process.
Edward Mallia
Oct 31st 2010, 15:34
The suggestion to channel roof run off into 'shallow boreholes' makes at least one valuable point: that the problem of run-off has to be treated near the head waters and not at Birkirkara or Msida. That apart, unless there are large numbers of 'shallow' boreholes to deal with roof catchments, they will fill up pretty quickly. 'Shallow' boreholes are not discharging to ground water; they are simply acting a s 'unlined' wells and should not fall under EU regulations.
There are some other points of concern in the report. It is not stated that connecting roof run-off to the sewage system is illegal; in the (also illegal) absence of a well in a private dwelling, run off should go on to the street. On the question of wells, a recent statement by Marco Cremona that well-water can carry Legionaire's disease, is probably incorrect; the bacterium requires water temperatures around 50C to flourish, which is why it flourishes in AC system cooling water. That apart, as pointed out by Paul Pace, 'retrofitting' wells in terrace housing and villas is not difficult. It does cost, however. In 1990 it cost me around LM350 for a small cistern.
Marco Cremona
Oct 31st 2010, 23:04
@Edward Mallia
Re.Legionella. I suggest you contact the Environmental Health Department with regards to statistics re. the number of detected (i.e. confirmed) cases of the presence of Legionella bacteria in premises/establishments arising from the use of untreated rainwater in cisterns. The risk is even high for those using bowser water and/or groundwater, but of course less in mains water. I for one, am aware of at least 3 cases in October in community residences only, two of which use rainwater!
The Legionella bacterium proliferates in temperatures higher than 25 deg.C, which is easily atttainable in roof tanks in the summer months. Optimum temperature is 37 deg.C. The bacterium starts to die off at temperatures of 50 deg C and higher.
Retrofitting cisterns in"terrace housing and villas". What % of our housing today is actually terraced houses and villas?
What I proposed is a effective 'retrofit' solution to those residences (of any type) that have ignored the cistern-in-every-dwelling law and which will continue to contribute to flooding (and deprive the country from catchment areas to recharge the aquifers) until they are demolished in 30-50 years time and (hopefully) be re-built with cisterns next time round.
Marco Cremona
Oct 31st 2010, 23:27
"the problem of run-off has to be treated near the head waters and not at Birkirkara or Msida. That apart, unless there are large numbers of 'shallow' boreholes to deal with roof catchments, they will fill up pretty quickly"
Individuals that have been 'selfish' enough to construct a basement and/or garage instead of a cistern or simply did not construct a cistern are contributing to flooding to the detriment of the general population.
Moreover, if the building is a new build it is depriving the aquifer from water recharge. If we were to apply the rule-of-law, these buildings should be demolished and a cistern constructed. Of course, this will never happen.
But in the spirit of the 'polluter pays principle' the owners of these residences should be fined an annual 'flood tax', which should continue to be paid until they rectify their situation and stop contributing flood water to the streets and/or the sewage network. So far the only solution is retrofitting a cistern.
Alternatively, they can install a ground-water recharge borehole. In effect, I am proposing a borehole for each building that does not have a cistern, irrespective of the location.
Frank Anderson
Oct 31st 2010, 15:25
This is a very dangerous, ill-concieved idea. What will stop people from lowering a water pump in 'their' borehole and start extracting groundwater? We now have a few hundred boreholes extracting water illegally, with Marco Cremona's idea we will have thousands!
The only people who will benefit from this 'idea' are the borehole drilling companies who would be applauding Marco's idea especially following loss of business from the proposed metering of illegal boreholes! Marco's suggestion will make the aquifer prone to contamination (e.g., people dumping oils etc..down their borehole, whereas leaking sewers will find a quick conduit to the aquifer).
Aquifer recharge needs to be meticulously controlled and I believe EU legislation exists on this matter. How can the government control what is happening in these Marco's proposed boreholes? By the way, has Ing Cremona told the public the cost of such boreholes? An average depth (circa 40 m) local borehole costs thousands of euro...to be paid by tenants according to Ing Cremona!
Ing Cremona's idea does not even deserve to be published. It is another addition to his 'simple' solutions to complex problems. I believe Marco has now lost all credibility as a water 'expert'.
Marco Cremona
Oct 31st 2010, 23:06
@Frank Anderson
Once again, I have to ask you..... what are YOUR solutions?
(perfect silence, again)
S. Camilleri
Oct 31st 2010, 13:48
Sorry but as well meaning as this may be it is way too simplistic. Unless your rain water catchment area is an impeccable clean surface, one cannot channel storm water run off directly. That would destroy the quality of what's left. Nature's way is to filter storm water through various layers of earth, large and small aggregates and rock until what finds itself into the water table is as clean as can be. Although, mother nature have not had time to adjust to the level of pollutants we are disseminating in our environment its filtration setup is still the most cost effective.
A Cassar
Oct 31st 2010, 15:08
I assume you are a qualified hydrologist, S.Camilleri?
Marco Cremona
Oct 31st 2010, 23:42
@S. Camilleri
I appreciate your concerns and I have attempted to reply to them in my subsequent comments. The major pollutants in our (drinking water) aquifers are chloride (i.e. salt) and nitrate, with concentrations exceeding 1000 mg/l and 70 mg/l respectively detected in most groundwater production sources.
Rainwater collected from rooftops contains less than 5 mg/l chloride and less than 1 mg/l nitrate. I trust that you can appreciate the 'cleansing' potential of some additional 20 million cubic metres per year of chloride-free, nitrate-free water reaching the aquifers.
I concede the fact that you will find the odd 'polluter' who will maliciously abuse the system, but this is mitigated by
1) the fact that the borehole will be as shallow as possible to retain the natural filtration capacity of the bedrock and
2) the dilution factor of a few litres of contamination in 20,000,000,000 litres of relatively clean rainwater will certainly sway the balance towards the idea.
This apart from the benefits of mitigating flooding at source.
Marco Cremona
Oct 31st 2010, 23:52
@S. Camilleri
It should be noted that the nitrate levels in our groundwater already exceed WHO/EU recommended levels and this trend will continue to increase for the next 40 years EVEN if we stop all sources of nitrate TODAY (i.e. artificial fertilizer, application of manure, leaks from the sewage system, leaking cesspits etc.). This is because the aquifer has a latent response, and the nitrate levels we are seeing today is the effect of nitrogen inputs in the 1970s.
Which means that unless we immediately find a huge source of nitate-free, clean water that goes into tens of millions of cubic metres a year that can be injected in the heart of the aquifer to dilute the existing high-nitrate groundwater, we will inevitably lose the use of groundwater for the potable water supply. I can think of no other free source of water than rainwater.
Treating sewage to potable water standard, pumping it towards the centre of the island and injecting it for groundwater recharge will be very expensive.
Felix Ebejer
Oct 31st 2010, 13:07
Il-Housing Estates ghandhom ikollhom gibjuni u l-ilma tal-bjut taghhom jinzel gol-gibjun. M'ghandhomx jiġu ttollerati l-ebda annimali fuq il-bjut u jekk hemm bzonn issir ligi ghalhekk u jkun hemm panali horox halli l-ilma kemm jista' jkun ma jkunx ikkontaminat.
John Mangion
Oct 31st 2010, 12:19
Whilst fully agreeing with the benefits of groundwater recharge, with clean rainwater, one needs to remember that discharges to groundwater are regulated by the EU Groundwater Directive, transposed in Maltese legislation by Legal Notice 203/2002 and amended by LN426/2007. Recharge initiatives will hence be required to align with these regulations to ensure a true improvement of groundwater quality as a result of the process
Raymond Sammut
Oct 31st 2010, 12:38
What you are saying in effect is that "recharging" (in accordance with regulations) and "channeling" storm-water (which would be virtually impossible to control under unusual conditions) are two different processes. The latter is most probably to be unsuitable, or at least very costly, in terms of satisfying the regulations. With storm-water, one is faced (potentially) with sudden and extremely large volumes. This would make "channeling" extremely risky.
Marco Cremona
Oct 31st 2010, 23:14
@John Mangion
I thank you for taking note of this article and providing your comments. I hope the Malta Resources Authority take it (and the comments hereunder) on board and seek to develop the idea further. I would be interested in partnering with MRA to seek local and EU research funding for the further development and subsequent implementation of the idea, provided the research shows that the idea is viable, of course.
Paul Barrett
Oct 31st 2010, 10:50
In theory this is a great idea however contamination either by accident or deliberate sabotage is not to be sniffed at. There is also the danger of eventually clogging up or filling up the water table area which would have the long term effect of making it totally useless. Currently the water table is protected by natural filters and natures filters should not be discounted or bypassed lightly.
Why disused quarries in suitable run off positions are not utilised as water catchment areas where water is either stored or if in the right position, used as filters to the water table is something that I cannot understand. It should also be possible to have catchment areas for major run off positions where rain water could be quickly pumped out as they start to fill to quarries or underground reservoirs for later use.
Raymond Sammut
Oct 31st 2010, 12:08
I was going to say the same thing in regard to potential contamination reaching the water table. I think that the opposite to what Mr Cremona is suggesting holds true. That is, rain water should not be allowed to find its way into boreholes. It's worse than water finding its way into the sewage network. Unfortunately, there is no easy, quick-fix, solution.
Immediately after WWII, Maltese governments built a large sewage network to reach all Maltese households. Historically, this infrastructure was most urgent at the time. Tragically, however, a parallel network for storm-water drainage was not put in place. The grave consequences of this short-sightedness in civic policy continued to be felt ever since.
The only solution is to commence --on a national scale-- long-term infrastructure projects that can channel storm-water towards valleys. Valleys, in turn, need to be re-opened and re-established with better roads and bridges put in place. Valleys also need to be walled and dammed, and equipped with seaward overflows. Of course, easier said than done, but this form of civil engineering is the only way.
Marco Cremona
Oct 31st 2010, 22:23
@Paul Barrett
My proposal included the installation of a silt trap to prevent/limit the transport of insoluble contaminants from being introduced into the tamper-proof borehole - because, yes, the carry-over of silt/dust will eventually reduce the ability of the borehole to dissipate rainwater.
It should also be noted that the groundwater protection zone of the aquifer is the relative high ground of Malta and Gozo i.e. in areas where the ground lies at a height of 75m or more above the aquifer. So, assuming that the depth of the water-dissipating borehole is say 10m, this still leaves 60m+ of filtration capacity. In areas outside the groundwater protection zone, i.e. around the periphery of the island, there is less risk of contaminants reaching the aquifer and of being pumped up for the potable water supply, also because the hydraulic gradient is towards the coast. However the influx of low-salinity rainwater will provide a fresh water barrier around the coast that will slow down seawater intrusion. Indeed this is behind MRA's artificial recharge proposals of using polished treated sewage effluent.
Marco Cremona
Oct 31st 2010, 22:41
@Paul Barrett
The use of disused quarries is much more risky from a water contamination point of view than the use of shallow boreholes. Firstly, stormwater runoff is contaminated by lots of nasty stuff like sewage, nitrate, pesticides, hydrocarbons and whatever litter (incl. toxic substances) may have been dumped on the roads, pavements, valleys and is carried away by the water. Rainwater collected from roofs does not generally contain this kind of contamination.
Secondly, quarries by nature are deep. Indeed, the bottom of most quarries is less than 10m above the aquifer. Consequently, quarries have very limited water filtration capacity and therefore pose a high risk as infiltration structures.
@Raymond Sammut.
Please make the very important distinction between relatively-clean runoff generated from rainwater falling on roofs and contaminated runoff flowing on roads as urban runoff. There is absolutely no comparison in terms of water quality. The former is only 3 simple stages away from drinking water standard - filtration, absorption, disinfection. Note: no expensive treatment as reverse osmosis (for removal of solutes).
Paul Pace
Oct 31st 2010, 10:50
I think that Marco Cemona's suggestion is the most simple, inexpensive and practical proposal in his personal campaign for the improvement of Malta's aquifers
Government, ( the Housng Authority or Water Services Corporation) may consider implementing this suggestion in housing estates where no individual will take this initiative.
My only reservation in this suggestion is that a small shallow borehole will be able to hold only a small amount of water. I know that it will seep slowly away but in a heavy rainfall it will be quickly filled up.
I alway used to dream of pits being dug up in residential areas (in squares or roundabouts), or even open war shelters, which can absorb storm waters from where water will slowly seep into the aquifers. But I now realise that that this type of water contains every type of contaminants which will actually damge the pure undergroung water. Therefore Marco's suggestion is sound because water coming from roofs is much less contaminated.
I disagree with Marco where he said that most newly built houses have no cisterns. All the persons I know who built their own houses do have wells. I think the problem is with blocks of flats.
I. Wright
Oct 31st 2010, 15:42
Inexpensive boreholes? do you know what is the cost of a borehole? it can easily run in the hundreds to thousands of euro!
Your suggestion of soak aways for rain water is a reasonable suggestion,but having more pirvate boreholes is ludicrous. What will stop people from lowering a pump to use these boreholes for illegal water extraction?
It seems that Marco is now in cahoots with the borehole companies after clamouring for metering of illegal boreholes which will cut a sizeable part of these borehole companies' business. I wonder, who is really behind these ideas? are their commercial interests behind Marco's suggestions?
Felix Ebejer
Oct 31st 2010, 16:11
I. Wright there would have been no need for private boreholes had the law requiring a cistern in every house been enforced. The owners did not abide by the law and they must now be forced to do so whatever the cost for them. We cannot continue allowing them to waste the water and causing floods by channeling it into the streets or worse into the sewage system and cause sewage overflows with the added dangers whenever it rains.
Marco Cremona
Oct 31st 2010, 19:56
@ Mr. Paul Pace
Unfortunately, this country does not have any statistics on rainwater cisterns in buildings. In a rare study on the subject, Claudine Cardona M.Sc. dissertation's on rainwater harvesting in Malta found a direct correlation between the presence of cisterns with the age of the building. That is, the older the building, the higher the probablility of that building having a rainwater cistern. It also follows that the likelihood of buildings built in the last 20-30 years (during a construction boom) having a cistern is very low.
Despite the requirement for the construction of a cistern in every building by law, we now have a legacy of thousands of buildings of all forms (apartments, terraced houses, maisonettes, high-rise buildings, villas etc.) that do not have a cistern. The result ? ... approximately 15% of our country's land area is generating relatively clean runoff (on roofs) which is collected - but which is not only lost to the sea, but contributes to flooding on its way to the sea.
Continued.....
Marco Cremona
Oct 31st 2010, 20:13
continued.....
Even worse is the fact that stormwater gets contaminated by sewage on its way- because of illegal connections of roof drains to the sewer network- causing surcharging of the sewerage system. The sewage mixes with runoff, resulting in large volumes of contaminated runoff running down our streets and valleys making this water more more of a liability than a resource.
The only positive aspect of having this water reach our valleys and infiltrate naturally is the fact that this water still has a salinity level that is less than groundwater, even though it has a certain degree of bacterial contamination, and some nitrate. Indeed, our aquifers exist because each year, despite the odds, a certain amount of water (approximately 50 million cubic metres a year) infiltrates into the ground and replenishes the aquifers.
At present, infiltration is happening in the unbuilt areas of Malta of Gozo, such as at 'pristine' garigue (on which there is no agricultural activity and therefore no agricultural contaminants- but probably a high lead content); cultivated areas (which result in an increase of nitrate in groundwater) and valleys, which contribute a mix of sewage-contaminated urban runoff and agricultural runoff.
Marco Cremona
Oct 31st 2010, 21:47
@I.Wright
I am very much aware of the cost of drilling a borehole. Yes, it's in the region of a few hundred euro for a relatively deep (c.100 - 150m) borehole. Yet this hasn't stopped more than 800 households from drilling boreholes to fill up their swimming-pools, and/or water their lawns, has it? In any case, I suggested the drilling of SHALLOW boreholes, and you may know that drilling is charged by the metre depth.
My solution is being put forward NOT as an alternative to the construction of rainwater cisterns BUT as a 'retro-fitting solution' (read as second best) to those who have committed the ILLEGALITY of not building a rainwater cistern. So I have no qualms for suggesting a solution that hurts their pockets and contributes towards the common good.
Given the building density of our urban areas, identifying and allocating areas specifically as soakaways will be very difficult, if not impossible. Apart from the fact that land (in building zones) comes at a premium.
To pump groundwater your borehole must be drilled to the depth of the aquifer. Shallow boreholes cannot be used to pump up water
Marco Cremona
Oct 31st 2010, 22:03
@I.Wright
"It seems that Marco is now in cahoots with the borehole companies after clamouring for metering of illegal boreholes which will cut a sizeable part of these borehole companies' business. ?"
Would love to know that my efforts in clamping on boreholes for the reduction in extraction may have had some effect :)
"I wonder, who is really behind these ideas? are their commercial interests behind Marco's suggestions?" Sorry to disappoint you but there's no substance to your conspiracy theory, just somebody who's got Malta's water at heart (and makes a rather lousy businessman).