Wednesday, February 20, 2008

More on Saving Water

I did a quick test and have continued my research, and calculated that we could save a minimum of 1,500 gallons a year. That's with very conservative values, and assuming that we hop in the shower as soon as the water gets hot. With the tankless heater and the new copper plumbing, it took less than 2 minutes for the water to get hot for a shower.

In reality, I don't stand there with my hand in the shower waiting for the exact moment the water gets hot, and I think our shower puts out more than 1.5 GPM. A more realistic estimate is 5,000 gallons a year. With current water EBMUD rates, that's about $16 a year in savings.

Which means it would take anywhere 12 to 82 years for a recirc system to pay for itself. That's not counting the small amount of electricity it would use on the minus side, and the unknown amount it would save on gas for heating water that's wasted on the plus side. So there's not much of a financial incentive to do it.

But I'll probably still go ahead with this, because while 1,500 to 5,000 gallons doesn't sound like much compared with annual usage totals, it's the equivalent of anywhere between 900 and 5,500 flushes of the toilet in a year. That's a lot of perfectly good drinking water to just flush away.

On the other hand, while rain barrels are a very cool, low-tech solution for saving water, even if I had nine 55-gallon barrels under the various downspouts and linked to each other, that's only 500 gallons that I could collect at a time. Given the wet winter and dry summer pattern here, that means besides some condensing fog, the last 500 gallons collected in April and May wouldn't see any company until October or November. So that may require some more thought, unless I get some free food-grade barrels offered to me.

7 comments:

Katarina said...

Ah, I know how we could get the recirc system to pay for itself more quickly: We could take more, but shorter, showers. For example, let's say I take a 12 minute shower and save 1.5 gallons of water with the recirc system. Well, I could save 3.0 gallons by taking two 6-minute showers instead, as long as I waited for a while in between to let the water get cold again.

(heh.)

Gene said...

I'm unable to argue with that logic :-)

And then there's this article from Kentucky about an $8,000 water bill. Not that I trust the comments on that site in general, but someone calculated that would be 400,000 gallons of water used in 2 months. That's what we'd probably save in 80 years with a hot water recirc system.

EBMUD's rates go up, so the more you use, the higher the rate you're charged. But if I'm doing the math right, at the rate we're charged (not including sewage fees), $8,000 would be 2,470,000 gallons in two months. Which would take 475 years for us to save.

Ay carumba! At least the hot water recirc would have paid for itself by then :-)

Eliz. said...

We installed a rain barrel last fall, and we use the water for the garden/yard. Just one barrel, you say? Well yes, but we are lucky enough to have several cisterns underground in what passes for a back yard on our tiny lot. So, we have one rain barrel that we can then drain into a cistern, and thus collect more water, more frequently. We pump the water out of the cistern as needed. It's not a perfect system, but it saves water and makes us feel like we are doing a little something to conserve resources.

What is most interesting to me is that water conservation is obviously not a new thing here in the heartland. Our house was built in 1912, and there are at least 3 cisterns in the yard, connected to downspouts via underground pipe (no longer functioning, alas). The house was originally plumbed to use the cistern water to flush toilets and other less-than-sanity household tasks. We haven't investigated reestablishing the cistern flush system (our pipes are old and fragile), but who knows...

Gene said...

Hmm...a cistern. I wonder how big of a tank I could bury in the back yard?

Paul said...

Cisterns are interesting, but consider that they pick up a lot of leaf debris and need to be cleaned out. I don't know about you, but climbing down in a hole in the ground to muck out the cistern is not among my favorite pastimes. Not to mention that you need to worry about proper ventilation since you wouldn't want to get low on O2 down there. (Why don't they let me use a subscript?...grumble...)

Only one our our three cisterns is not completely full with dirt and rocks. But we still use that one for storing water. We could store a lot more if I cleaned it out, but I'm NOT looking forward to that task. Besides, I don't know what I would do with ~500 "gallons" of dirt and rocks.

stephanie said...

hi. i found your site via your comment about your tankless hot water heater on the enon hall forum. i'm a new first-time homeowner (also in oakland) who just got cited by the city, during my electrical inspection, because the new-ish hot water heater (installed by the previous owner) is not installed per code. we need to correct it asap because the inspector will not sign off on the electrical rough in until it is corrected! also, we need to be out of our apartment and in our new (old) home very very soon and we are without power in the house until this is all resolved.

anyway, if i need to go with a new water heater, i'd like to go tankless, but i'm shocked by the first estimate i got yesterday--almost $9k! did you install yours yourself? if you didn't, would you recommend the person/company that did?

also, our friends at casa decrepit have been successfully playing with total water recycling, if you want to check it out.

thanks.

Gene said...

We had LJ Kruse install it about 4 or 5 years ago. I don't recall exactly, but it was around $3.5K, so $9K sounds absurd. I didn't do the work myself because (a) this was 4 or 5 years ago, before I was as comfortable doing everything myself (b) it involved changing the gas line and (c) it involved installing a special vent for it. The old water heater vented up through the chimney (along with the furnace), but if I recall correctly, that may no longer be allowed. But it wasn't allowed for the tankless in any event because it needed a special vent.

Thanks for the link to the water stuff Casa Decrepit did.