Greggd,
I replied to a similar post of yours on another of the forums about feasibility of the general idea of water towers for hydro. I see now that I missed that you are "on the (water) grid" - e.g. planning to use the municipal pressure to put the water in the tank... and hence would have an essentially unlimited supply of water.
The slight ethical question another poster raised about "what if everyone did it?" is mooted by a reply that raises a bigger question. The reason you are not overusing your share of some ideal "community water pressure" supply is that they (presumably) charge you for municipal water. And I assume that charge is paying for their costs to pump it and pressurize it (in our town that is to another much larger village-owned tower. The real issue then becomes how much you would pay for large amounts of water.
But I see that you are probably not proposing using tens of thousands of gallons of municipal water per day to drive a hydro system !
Which means (please clarify if not) that you are planning to basically cycle your daily use through such a system.
With this we can use an analysis similar to what I posted on the other forum to calculate energy available based on volume of water and amount of "head" (drop).
Average 4-person household use of indoor water is 400 gallons per day. At 8 pounds per gallon that's 3200 pounds of water. Drop that 14 feet and you have 44,800 foot-pounds of work.
40 foot-pounds of work in a second is 50 watts of energy for one second. 1 foot-pound is 1.25 watts. But you wouldn't use all that water in one second.
If you ran all 400 gallons of your daily usage through a 100% efficient generator over the
course of ONE HOUR (3600 seconds) that would give you about 12 foot-pounds each second or 15 watts continuously.
Not sure its a keeper ?!
D.
same caveat as before !! I'm no expert - just someone who has wandered these paths numerically for a while.