5 questions on building water-friendly

Over forty percent of the water we use in and around the house does not have to be of drinking water quality at all. We can also use captured rainwater or purified greywater.

Vitens – the largest water utility in The Netherlands – is therefore committed to water-friendly construction. In the design phase of new homes, the installation of alternative water supplies is already taken into account. Micha van Aken, Business Development Manager at Vitens, explains what is involved.

The drinking water in the Netherlands is of excellent quality. That is the result of more than 100 years’ work on a safe and reliable drinking water supply. However, we also use this drinking water to flush the toilet or water the garden. What a shame! Often you can use water of lesser quality. Rainwater or greywater, for example. Water for domestic use that is not of drinking water quality is also called domestic water.

Installing an alternative mains network in existing homes is often difficult and expensive. That is why Vitens wants to encourage people to think carefully about the installation of drainage and alternative water pipes during the design phase of new homes in order to separate the use of high and low quality water in and around the home.

Micha van Aken is Vitens’ point of contact when it comes to water-friendly construction. He has a lot of contact with contractors, governments, and other relations about these kinds of solutions. We ask him 5 questions:

Why is water conservation important?

“Because the demand for drinking water sometimes exceeds the supply. At certain peak times – in the summer, when it’s very hot and there’s a lot of use – it can happen that more water is used than our production plants can make in a day. This is a development that started many years ago. Compared to about 1950, the demand for drinking water has increased by 400 percent, while the population has only increased by 70 percent during the same period. This has to do with behavior and comfort. We bathe and shower more often and longer, use appliances to wash clothes and dishes, wash the car, water the garden… In other words, we use drinking water much more than we used to. Drinking water has long ceased to be used only as a primary necessity of life. We are therefore already investing heavily in expanding capacity, but even then it remains to be seen whether we can keep up with the growth in drinking water consumption. That’s why water conservation has been an important part of Vitens’ strategy for the past year and a half.”

What is the concrete benefit of water conservation for a municipality, for example?

“If less drinking water is needed, you don’t have to pump up as much groundwater. That’s better for all sorts of things: for nature, agriculture, basically the entire water system. By opting for water-friendly construction in the development of new buildings, not only is less drinking water used but the municipal sewerage system is also relieved of the burden. For example, by locally collecting and purifying rainwater and gray water for reuse in and around the home. This is good for a municipality. Less storage is then needed for rainwater and less sewer capacity.“

What is water-friendly construction?

“Taking the use of water into account already when building. That can be done in different ways. For example, do we go for collecting rainwater, as is already mandatory in Belgium, to use for the garden or the toilet? We are currently running various pilot projects at Vitens to look at what is involved in water-friendly construction. These vary from simple to complex.

For example, you can ensure that you lay the pipework in the house in such a way that you can easily connect a new system to it afterward. The builder or resident does not have to choose a particular system at that time. But if the resident would like an alternative system later, for example, to flush the toilet with rainwater, then that is possible. Without any cutting and demolition work.

Then there are devices such as the Hydraloop to purify and reuse slightly contaminated wastewater from the house – greywater – at the house level. We are also investigating collective systems whereby domestic water is produced from rainwater, excess groundwater or greywater at the building or district level. Hopefully, these kinds of individual and collective systems will continue to develop in the coming years, so that they will become increasingly affordable and efficient and therefore widely applicable.

If you think about these kinds of solutions at the front end, you ensure that you build houses that are prepared for future developments and wishes. I often hear from governments and builders that they do not think much about water use in and around the house. When people think of sustainable building, they often think of energy, insulation, and the use of materials. But not often about saving drinking water. It’s time for that to change.“

How can I build water-friendly as a contractor, homeowner, or government?

“By already collecting rainwater in new construction projects. And by taking into account the possibility of connecting alternative systems later. With the pilots, we are looking at how feasible the various initiatives are, what is useful and what is not. As soon as we find out what works well, we can disseminate it widely and work towards making water-friendly living easier.

The building task in the Netherlands is huge. And it is not yet the case that all toilets are flushed with domestic water. If you now ensure that rainwater is collected separately and stored somewhere in a buffer, and you collect the wastewater (gray water) separately, purify it for reuse and ensure that the piping is kept separate, you are already well on your way.

It would be even better if collective solutions for water-friendly construction also considered the collection and purification of wastewater in a smart way. At present, there is often only one water pipe going in and one outlet for wastewater going out. But if you add more options in new construction, you ensure that in the future, without hacking and demolition work, you can deal with water in and around the house in a different way. This flexibility is important. Because we may not always have a ready-made solution now, but in the future, we will. Because a building is not there for the next five years, but often for a hundred.“

How do I ensure that the regular drinking water and piping system is not at risk of contamination?

“They are two different systems that should not come into contact with each other. And so in the pilots, we are looking closely at how we can guarantee safety. For example, by using different colors or different types of pipes for alternative pipes. The quality of drinking water is monitored extremely carefully, and the same applies to the quality of purified rainwater or greywater for flushing toilets. RIVM and the Environment and Transport Inspectorate are happy to monitor our pilots to follow new developments of this kind.“

This article was originally written in Dutch and published on the website of Vitens. The copyright lies with Vitens.