mains water recycling

[minihydro]

i am a student looking into recycling some of the mains water pressure into electricity on a small domestic scale. where would be the best place in a domestic plumbing system to get some of this power back?

[Postdog]

I'm not a student, and I have no qualifications in this, nor any real interest as such, but I don't think it would be viable or possible. The only time - as far as I can see - that there would be any energy in the water to reclaim would be when the water was actually flowing, ie, the taps were turned on (sort of like a river with a water wheel). Unless you used the water 24/7, which you wouldn't, you'd get very little energy from it.

[gasman]

Well the best place to start would be the toilet cistern every time it is flushed it will gush water as it fills back up; as will the hot water header tank, when someone is running a bath or shower. i suppose theoretically you could harness the energy from the running water from these outlets. Or even from the waste outlets when the bath is emptying maybe or the washing machine is in use. Just a couple of thoughts for you there.

[Toureman]

Using the waste water system would not give enough pressure to turn any sort of turbine to produce electricity.

The best place would be in the pipe that supplies the water before any take offs, taps etc.

If anyone started using this system I am sure it would be declared illegal as people would just run taps all the time so producing free electricity, causing more droughts than we already have.

[buildersmate]

Agree with Toureman, para2.
And para 3 - its not really a feasible idea.

[heathfield]

Interesting concept... Reminds me of something I read in the 60s.
An Australian company produced a great design for a solar water heater. It consisted of a large parabolic sheet of polished aluminium standing upright, that focussed the sun's rays on a water pipe to heat the water. The device was turned to face the sun by using mains water pressure. Under each outer edge of the sheet was a long brass rod. If the sun shone on one of the rods, the rod would expand, opening a valve that caused the reflector to slowly turn to again face the sun, which put both rods back in the shade again. Each night after sunset, the whole thing turned to face east, ready for next morning.
D'you think I can find any reference to this whizz of a heater these days? Nope.

[jake-the-peg]

Did you see the series "It's not easy being green"?

They ran an entire stream over a waterwheel and generated just enough energy to run a dozen or so low-energy lightbulbs.

I think you'd be lucky to run 1 low energy bulb every time you flush the loo.

Maybe you could illuminate a sign for a few seconds saying " Now wash your hands" :c)

Nice Idea - I just don't think the maths will work

[rccatnap]

I agree with the others. Rather than use the continuous motion of the water, which has been stated is not happening that often, the only viable way to harness any power would be to store it in a battery. However, the cost of doing so would far outweigh any real benefit.