We're doing our bit to save water. By diverting all our washing machine water onto the garden, I reckon I've done enough to justify throwing out our stupid, useless "water saving" showerhead and replacing it with something the size of a dinner plate with 1/4 inch holes drilled all over it.
But what will happen if everyone stops sending their washing machine suds down the drain and pours it over the lawn instead? Will this have some sort of horrible consequences for our sewerage system?
If washing cothes makes up something like 10% of household water consumption, presumably the amount flowing into the sewers will drop by 10% or so. There'll also be a big drop in the amount of suds going into the system - having a shower just doesn't consume the same amount of soap powder as a couple of loads of kids clothes per day. Will the lack of suds upset the delicate ecosystem of the sewerage system? Is this the sort of thing that gives water engineers nightmares?
When you add in all the rainwater tanks that are going in, which will surely reduce the amount of water going into the storm water system, will we find that the big surges of water during big downfalls become a thing of the past, and our systems no longer get a good flushing on a regular basis?
For all I know, these could be good things. But then they might be bad things.
Whatever they are, they are unintended consequences.