Despite the huge amount of money Malta spends to desalinate water, millions of litres of rainwater are lost each year due to poor catchment. Massimo Farrugia finds out how a simple project in each home could save the country millions of liri in water production and flood mitigation costs.
It's simple. So simple that you wouldn't normally give it much thought unless you are obsessed with water like Marco Cremona, a hydrologist and water treatment engineer. He has reached a stage where he can almost remove the mains tap of his house in Mosta and rely solely on rainwater.
Despite his vast knowledge in the subject, Mr Cremona used primary school arithmetic and a year's experience with his own system at home to arrive at the conclusion that by utilising rain water, a typical Maltese family of three to four living in an average-sized house can save more than two-thirds of their water bills if they collect the rain water which falls on their roof.
What's more, the country's water production costs would go down by up to Lm8 million each year if the system were adopted nationwide.
"By pumping rain water from a well up to the mains water tank on the roof, and using the water for all uses every day, even in winter, an average family can be self-sufficient for seven whole months between October and April," he claims.
Mr Cremona advises against the use of well water for drinking purposes without appropriate treatment. "It may however come as a surprise to many that drinking water accounts for less than two per cent of a household's typical consumption - so the water savings related to drinking water are minimal in any case," he said.
According to Mr Cremona's estimates, a typical household would save 67 per cent of its average water use (the latter estimated at around 240 litres per household per day) with a 6.5 cubic metre well or tank and the standard one cubic metre roof tank.
"This will equate to a monetary savings of Lm72 per year (to be knocked off a typical water bill of around Lm94 per year). When calculated with the 55 per cent surcharge, this represents a 76 per cent savings in the water bill," he said.
But how does one come to such estimates? Using official rainfall figures for each month of the year, Mr Cremona calculated the amount of water that falls each month on the roof of a typical house.
"If in January, for example, 86mm of rain are registered by the Meteorological Office, it means that the total rain water falling on a 100m2 roof is equal to 8.6 cubic metres (8,600 litres) of rain water. Evaporation loss from roofs is minimal so in practice all the rainwater falling on the premises can be collected. Spread over 31 days, the average rainfall in January equates to 277.4 litres of supply per day, which is 39.4 litres more than the average daily need of a family of three to four members.
"The daily household water requirement is automatically pumped to the roof tank for use on a daily basis. The surplus will remain in the well for use on a 'dry' day.
"Hence the need for a small amount of water storage capacity. Rainwater will continue to supply the household until it stops raining and households will have to open their mains again towards mid-spring," Mr Cremona explained.
The project entails a one-time cost of about Lm150 to install the water pump and its electrical control and an Ultra Violet (UV) system which kills any bacteria that may be present in the water. With a 55 per cent surcharge on water bills, costs would be recuperated within the first two-and-a-half years.
This calculation takes into account the cost of electricity consumed by the electric pump and UV system, as well as the annual replacement of the UV lamp which sum up to about Lm20 a year.
That's fine for those houses which already have a well or a cistern. But what about those which don't?
"A 6.5-cubic-metre tank is roughly half the space occupied by a car, so it can be easily retrofitted in a basement. The only problem would be for rented properties and flats or houses in high rise buildings, where ownership issues relating to the roof and basement may come up" Mr Cremona said.
"Unfortunately, most houses built in the last 30 or so years do not have a well, with the result that rain falling on these properties results in flooding and overloading of the sewerage network".
The law that each newly built house should have a cistern with about 50-60 cubic metre capacity has been in place since the 19th century, even if it has not always been enforced.
In his own house, he plans to achieve 100 per cent self-sufficiency through the use of a "grey water" recycling system and simple water conservation measures.
"I have a separate system to collect waste water from showers and from the washing machine and use it to flush toilets after filtering it," he said.
Mr Cremona thinks that it is high time that Malta puts into action a national water saving strategy which incorporates simple, practical measures at a domestic level.
"It's a question of coming up with truly innovative methods and implementing them," he said.
The strength of Mr Cremona's conclusions lies also in their relevance in reducing costs involved in reverse osmosis water production.
"The country would save up to Lm8 million a year in reduced water production costs as full implementation of this system in households would result in a reduced national water production of about 40 per cent.
This also equates to a reduction in electricity generation of about 2.6 per cent which is today being used in water production and distribution," he said.
With the system in place, the amount of water that would be diverted from roads and the sewerage system during storms would be about 6.5 million cubic metres a year.
"Dealing with water flooding without the domestic water collection systems would necessitate an upgrade of our existing national storm water collection infrastructure by 10 times its exiting capacity."
The truly indispensable resource
Water is deemed humankind's most precious resource. Population growth and economic development have over the past 50 years tripled demand for water.
The largest user of fresh water is agriculture, which amounts to 75 per cent of its total use worldwide. That figure is 90 per cent in Africa. Due to its increased use in many industries, fresh water supply is being withdrawn at a faster rate than it can be replenished. In 2000, global water withdrawal is estimated to have been 1,000 cubic miles, equivalent to 30 per cent of the earth's total accessible fresh water supply for that year. That figure will at least double in 20 years' time.
The World Health Organisation estimates that 1.1 billion people in the world lack access to clean water supplies while 2.4 billion lack access to basic sanitation. Water shortages now plague almost every country in North Africa and the Middle East. By 2050, the number of people lacking access to clean water will decrease further.
Flood relief project proposed
The national paralysis which strikes the country each time a storm hits the Maltese Islands is the result of years of building without proper planning. This is the case being made by Resources and Infrastructure Minister Ninu Zammit in his effort to push through a proposed multi-million liri flood relief project to divert storm water into 15 kilometres of underground tunnels.
The ministry has drafted designs over the past two years to build a cylindrical tunnel beneath Mosta, Naxxar, Iklin, Birkirkara, Msida and Lija, a spokesman for Mr Zammit said.
"The aim is to collect and dispose of storm water which could be used to irrigate green areas and for cleaning roads besides tackling the huge flooding problem," the spokesman said.
If approved by the cabinet, 85 per cent of the project will be financed by European Union structural funds. The project may take four to six years to complete.
Water reuse system... facts and figures
Using the rainwater reuse system, a family would save about 67 per cent of water supplied through the mains.
If a family consumes 87 cubic metres of water per year and 58 cubic metres are recuperated through the rainwater collection system, it would be self-sufficient for seven months of the year.
Translated financially, it means paying Lm22.19 instead of Lm93.91 per year at present in Water Services Corporation tariffs (16c5 per person for the first 11 cubic metres consumed and Lm1.10c for each unit above 11 cubic metres plus a 55 per cent surcharge). This would mean saving Lm71.72.