Lord Cromwell (CB)

My Lords, I assure the noble Baroness, Lady Bennett, that many good things come from Australia, and she is one of them. The tapping on the tank she describes is exactly what I have been doing in Leicestershire in recent weeks. I have some experience of water harvesting, both from domestic roofs and from commercial buildings, and actually it is not very difficult, because roofs are all designed to channel water into pipes, and it is simply a matter of intercepting that water and using it. I do have a couple of practical concerns. The first is that, as anybody who has done this will know, even a modest rain shower will give you an awful lot of water. As a result, any housing development or business premises is going to find itself with a very large need for water storage somewhere on that site, either underground or above ground. My second concern is how that water is recycled. I am not squeamish about drinking or using non-mains water. I raised a family on water drawn from an underground stream, not on the mains at all. But water left standing in a tank will grow bad and grow algae very quickly. If that is the solution, we need to find out how to treat it. Furthermore, there is a real issue that I run into: the water companies and Ofwat will not even contemplate the danger of mingling water collected by a third party with mains water—in a header tank, in your pipes or anywhere else—because they are liable for the quality of that water. So, if you mingle it with rainwater, they will not allow you to draw mains water. The golden thread here is to find a system where rainwater is the norm and the mains is the back-up, but we are a long way from that at the moment and will be until the regulatory and practical storage issues are solved. To be clear, I thoroughly support this amendment—the spirit of it—but the practicalities of it need to be worked out effectively into the design of water systems supplying domestic and commercial premises.