There are increasing calls for the installation of a separate water system in new housing estates, where rainwater can be used to flush the toilet, for example. The Drenthe drinking water company WMD does not like this. Why not?
When you talk about scarcity, you will hear the word ‘water’ used in the same sentence more and more often in the coming years.
We have to save money, that urgency is well known. Particularly during dry periods, there is a risk that too little drinking water can be extracted. Vitens boss Jelle Hannema and his drinking water company supply 6 million customers in Friesland, Flevoland, Utrecht, Gelderland and Overijssel. He recently asked himself in the Volkskrant out loud whether it would still be able to supply enough water in the coming years.
In Belgium, rainwater is used in households slowly saving drinking water . In our southern neighbors this was included in the Building Decree in 2004: new houses will have a separate rainwater collection for the toilet, washing machine and outside tap. Belgians – in 23rd place for the most water-scarce countries in the world – feel that need more than we do.
But there are also plans in the Netherlands to connect new-build homes to rainwater. For example, at the end of last year the House of Representatives adopted a motion for the use of rainwater in homes.
Forced by national shortages and an adopted parliamentary motion, the cabinet left last year research by the Witteveen en Bos bureau to the possibility of using rainwater or greywater (wastewater, for example after showering). The researchers conclude that a separated system is indeed an opportunity to enforce less drinking water use. But they also write that ‘the use of rainwater or graywater is not risk-free’.
Not sustainable and not healthy
Because of these risks, Drenthe drinking water company WMD considers a separate system to be a disastrous route. “We believe that capturing rainwater for households does not work,” says Roald Leemrijse, public affairs manager. “That water is desperately needed in residential areas, partly due to climate change, for local greenery, gardens, biodiversity and cooling in dry summers.” Ultimately, through infiltration, rainwater also benefits the groundwater from which drinking water is made.
There are all kinds of reasons not to want this, Leemrijse lists. “How sustainable is it to use all kinds of extra materials for such water savings – a concrete pit, pipes, plastic rain barrel – and electricity for filters and pumps?”
Even more important is the objection on grounds of public health. “There is a good chance that there will be a wrong connection and that people will then drink rainwater. That is really not healthy,” says colleague Henk Brink, quality manager at WMD. The water contains disease-causing micro-organisms, bird droppings, chemicals and pesticides. “Once you have such a rainwater hose, it happens that people accidentally make connections that lead to drinking water taps.”
He points to experiences from Leidsche Rijn, where such a rainwater hose also ran through the houses. The management was deliberately colored differently and the technicians had to take special courses. Yet things went wrong and in 2001 there were two cases in which people ended up drinking rainwater. The GGD Utrecht concluded later that it was likely that some of the residents in the neighborhood had developed health problems due to contaminated drinking water.
Too expensive
WMD has one more final shot ready for the plan: there are cheaper alternatives. They had research done into this, also by the Witteveen en Bos agency.
A calculation. Installing a separate system in a new-build home costs 4,500 to 7,500 euros. According to plans, approximately 13,600 new homes will be built in Drenthe by 2030, so the new owners will jointly pay 60 to 100 million euros for such a system. If all households in Drenthe were to receive such a system, you would even be talking about costs of up to 1.7 billion. According to WMD calculations, this saves consumers less than ten euros in cost savings. “Very different from solar panels, which you can earn back,” explains Leemrijse.
According to the drinking water company, the alternative is deadly simple: retain more water in the ditches, streams and lakes. Costs: more than 18 million euros. That is possible, because there is a precipitation surplus of 70 to 80 percent in Drenthe. The reason why this is not yet happening is mainly due to farmers who cannot enter the land if it is too wet. But according to the WMD strategists, there are still plenty of places where water can be retained even better. The water company also wants to work on infiltration of water into deep ground layers at Assen-Oost for a larger underground water buffer.
Gronings Waterbedrijf has a different approach to the competition
But the view of the Drenthe water drinking company is not universally shared. There is a reason for this: the WMD has relatively better resources and reserves than neighboring water companies such as Vitens and Waterbedrijf Groningen.
Wout Kompagnie, policy advisor at Waterbedrijf Groningen, sees opportunities for a separate system. “We flush 25 percent of our drinking water down the toilet. That is 30 liters per day. If you were to use rainwater for this, you are talking about significant savings.”
He sees the same disadvantages as the WMD. “But for us there is a greater urgency to save drinking water, so anything that allows us to save water is a bonus.” His water company can pump water in far fewer places due to the salty subsurface.
Good agreements, and preferably ‘grey water’
If you opt for separate systems, Kompagnie emphasizes that good agreements must be made about how the health and sustainability of the new system is guaranteed. Kompagnie also sees merit in smarter applications within the home, such as reusing shower water for other purposes. For example, there are systems where the toilet flush does not use 6 liters to 2 liters. “You just scoop the turd out of the pot this way, and it goes into the sewer with shower water.”
This is cheaper than a separate rainwater system and is easier to install in existing homes. Another advantage of using this ‘grey water’ is that the inflow is more constant than rainwater. “People still continue to shower. But the rule for rainwater is that it runs out during a longer dry period, and that is exactly the moment when water demand peaks.”
How do you save water? Five tips
1. If you want to save, you will make by far the most profit in the bathroom. Your shower accounts for about 30 percent of your total daily water consumption; One minute shorter shower saves 8.5 liters of water.
2. There are all kinds of technical methods to reduce water consumption. A savings button on the toilet saves up to 3 liters per day. E and water-saving shower head saves 20 percent water and energy. Speaking of technical solutions: v Fix a dripping tap as quickly as possible, which will save up to a thousand liters per year.
3. If you still have the tap open when brushing your teeth: turn it off, which saves up to 10 liters per minute.
4. Although rainwater indoors is not ideal according to drinking water company WMD, there is nothing wrong with collecting water outdoors for watering plants or washing the car. Fifteen minutes of watering from the rain barrel saves up to 100 liters of drinking water. On hot days you can safely let your grass turn yellow. It’s a matter of accepting it, it will recover.
5. In any case, you can save a lot by organizing the garden differently. Replace tiles with plants and then choose (native) plants that can withstand drought, such as v ears, clovers, succulents and composites. It is better not to plant plants that are more thirsty in the sunniest corner of your garden. Z also occurs in such a climate-proof garden ground cover plants to prevent the soil from losing unnecessary moisture. You can also place tree bark on bare pieces of ground.
Tags: Rainwater toilets solution Drenthe drinking water company WMD Water Company Groningen
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