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bennelson 03-11-09 10:06 PM

Ben's DIY Graywater System
For a while, I have been thinking about some sort of graywater system.

My house uses a "holding tank", which is just to say that the waste-water from the house goes into a 2000 gallon tank buried in the backyard.

A holding tank is much cheaper to instal, but much more expensive to maintain in the long-run. That's because you have to pay somebody to empty it every time it's full.

It costs about $90 to empty. How often? Well, at my house it's about every 5 or 6 weeks. That means water cost more than gas or electricity at my house, which also means it should be a priority on my EcoRenovating.

(And no, please do not start a discussion about getting a septic tank or municipal sewer at my house. Septic tank would have to be above ground, cost about $15,000 and literally take up my entire back yard. Municipal sewer is not available, and even if it was, still costs money, although less than what I currently pay!)

Anyways, what seems to make sense is one of two things (or both!).
1) Run water to someplace other than the holding tank. (The yard or garden for example.)
2) Reuse the water inside the house before running it down the drain.

I really don't want sudsy bubbles in my side yard, and the garden is pretty far away - uphill, so lets focus on option 2.

Both of these options are considered "graywater" - water which has been used, but could still be used again for, say, watering plants. This is different from "blackwater" which is what goes down the drain from the toilet.

Speaking of toilets, that would be a great place to SEND graywater. Why do we flush our toilets with perfectly good drinking water? That doesn't make sense!

Instead, why not use water doing down the drain of the sink, the shower, or someplace else to fill the toilet tank?

I have kept kicking around the idea of using waste shower water to feed the toilet. I take a shower every day.....I use the toilet every day.....It makes sense. Both are right near each other.

HOWEVER! I am limited in space. My house is over a concrete enclosed crawl-space. (Think a full basement, which is only 22 inches tall!) That leaves me little room for a basement water tank or ease of accessing any sort of filter system.

Today, it dawned on me that the clothes washer would make a better option for a graywater source to feed the toilet.

Here's why:
Crawl space access is 2 feet away from the washer.
Laundry drain is VERY easily accessable
Water storage tank could be located in laundry room instead of in crawl-space.
Laundry puts out rather "clean" dirty water - no chunks of bar soap or long hairs!

The only real disadvantage is that the laundry room is farther away from the toilet than the shower is. But that's not a big deal, it just means I need more pipe. I think the extra expense of 20' of small-diameter pipe is worth it.
In the above photo, you can see that there is some space between the utility tub (on the right) and the clothes washer (in the middle)
There's still about 8" between the the washer and the dryer (on the left.)

If I moved the washer as far to the left as I could, I think the space between the utility tub and the washer is big enough to hold a custom water tank. The washer uses about 20 gallons per load. I think I could fit a 40 gallon tank in, but maybe not a 60. How big is a gallon? I might have to do some 3-dimensional math to figure out how many gallons fit in a space 30 inches deep by 30 inches tall by X wide.

The downside to this is that we DO shower every day, but we do NOT do laundry every day! Still, that would mean that all the water we use for laundry would be "free" as it saves us from flushing other water down the toilet drain!

Please expect this project to be "long-term", as I still need to Ecomod my electric car to 144 volts, convert my pickup truck to bio-diesel, build my wife a greenhouse, get off gasoline and corn syrup........ The list goes on! :eek:

All positive ideas and comments welcome.


PS: Also in the photo, you can see the trap door that allows me access to the crawl-space. That's the only way to get under the floor to work on plumbing or anything else I would build down there.

Daox 03-12-09 07:23 AM

I think a greywater system would be perfect for your situation. Your idea is also pretty good IMO. The washer will fill up the tank you have in the laundry room. If its full, overflow would go to your holding tank. Then, I'd setup a switching system inside the toilet with the float to turn on a pump that would pump water into the toilet tank after it is flushed. Pretty simple setup and not too expensive either.

TimJFowler 03-12-09 12:59 PM

I found a nice Grey Water resource with several examples of DIY grey water systems. There is also a grey water system selection chart which lists pros and cons of various system designs.


wyatt 03-12-09 01:39 PM

1 cubic foot is 1728 cubic inches
the 30" by 30" space is 900 cubic inches per inch of width
1 cubic foot is about 7.5 gallons

So... every 2 inches of width would be about 7.5 gallons, or 3.75 gallons per inch
The picture looks like over a foot of space to be had... or around 40 gallons, like your guesstimate.

Perry525 03-13-09 07:11 AM

Grey water
Grey water is inclined to smell, therefore it needs to be cleaned up before use, running it through a sand box, then pumping it up to the top of the garden, will loose most of it in evaporation and absorption. such that is left will merely make its way down hill and disappear.

bennelson 03-13-09 10:20 AM

Here you can see the laundry machines pulled away from the wall. The washer has two black hoses supplying hot and cold water to the washer. The black "bendy" pipe going to the wall is the waste-water output pipe. It simply hooks down into a drain pipe built into the wall.

In the background you can see the natural gas supply line to the dryer and the air exhaust pipe out through the wall. That had a bad air leak there, so I sealed and insulated the connection to the wall before pushing the dryer back.

you can see the washer exhaust hose just hooked onto the utility tub. The fact that the washer has a simple hose like this makes the plumbing a little easier.

With the counter-top removed and the dryer hose insulated, I then pushed both laundry machines over as far as I could (and still be able to open the doors!) and was left with just under 17 inches between the dryer and the utility tub.

That's great, because 16 inches tends to be a "standard" size for manufactured items. I may be able to find some sort of industrial bin that's 16 inches wide.

The space of 16"W by 28" deep by 34" high would be about 60 gallon capacity. That's 3 loads of laundry.

My toilet is marked as "1.6 gallons per flush", but it also has a brick in it, and is rigged only to flush as long as the handle is held down, so you can vary water usage depending on #1 or #2.

At 1.6 gal/flush the graywater tank would hold 37 flushes!

I like the idea of controlling a pump with the float in the toilet tank. That would be pretty simple - pump water when the toilet needs it, stop the pump when it's full!

I still don't know what kind of pump or pressure device might be needed to make this really work. Any suggestions on that?

An overflow for the graywater tank would be easy as well, because I could just route that to the utility tub.

Anyone have a 16 by 28 by 34 (or taller, to be cut down) container? Know of what container may fit that bill?

PS - In terms of routing graywater to the garden or other outdoor use, the garden is pretty far away, uphill, and I am in Wisconsin, so I wouldn't be able to use the system in the winter, as it would just freeze. One great thing about re-using graywater inside the house is that it doesn't freeze!

cmittle 03-13-09 09:40 PM

At first glance I thought it would be easy to get a pump for this situation. I imagine you'd prefer an ac (vs dc) pump for this application? Shurflo is the first thing that came to mind. This would probably work, but it's a little more expensive than I had thought it would be at $130. It flows 3.3 GPM which would mean your tank would fill in about 20 something seconds. That seems like a long time to me.

Or here's another one which should fill your tank in ~12 seconds for about the same price.

Maybe you should get an expected fill time to work with that will help you determine the flow rate of pump you'll need.

bennelson 03-14-09 03:06 PM

That FloJet Quad looks like a pretty decent pump. I would prefer AC, as I have no PV electric at my house. (Although I could run a DC pump off a DC adapter if I found a really good deal on a DC pump)

I like the idea of a pump with a built in pressure on/off switch. That would mean that I wouldn't have to do any work with a switch in the toilet running off the float or anything like that.

I guess RV pumps work in a similar fashion. I know a guy who is an RV mechanic, and may be able to get one through him.

bennelson 03-23-09 05:33 PM

Well, I have played around a little more with a "mock-up" graywater system.

I had a 30 gallon barrel in my laundry room, which the output from the washer goes to.

In the barrel, I dropped in a submersible "power-head" pump from an aquarium, connected to a garden hose. A powerhead is the exact size to fit into the cut-tube-end of a garden hose in case you were ever wondering.

The other end of the hose went right into the top of the toilet (with the lid removed), held in place by an Eco-Clamp. (Green-handled spring-clamp)

The pump was connected to wall power through a remote on/off switch, sold as an easy way to turn your X-mas lights on and off in the winter.

Use the toilet.
Press the button to turn on the pump.
Watch the toilet tank fill up with graywater.
Press the button to turn off the pump.

Go do something else until you have to use the toilet again, then come back and repeat.

After looking at how a typical well-fed plumbing system works. I think I will do something similar.

Have a pump that turns on and off with a pressure switch. Use a small pressure tank. The pressure tank will feed water to the toilet, and the pump will automatically turn on and off only as needed. I think I just need a check valve in there somewhere!

This is very similar to how the power brakes on my electric car work! :thumbup:

Can anyone tell me what the difference between a Pressure Tank and a Thermal Expansion Tank is? I can get a 2-gallon Thermal Expansion tank for $5! Sounds like a pressure tank to me!

bennelson 03-25-09 08:36 PM

I bought the 2 gallon pressure tank, a 1/2 HP Shallow Well Jet Pump, a cartridge filter, pressure gauge, check valve, and lots of little connections to make everything fit together.

For my line to run to the toilet, I bought 25' of 1/2" PEX plastic water line.

It's light and flexy, which is great, because my crawl-space has such limited access, that it would be hard to fit 10' sections of rigid pipe down there.

I spent WAY too much time at the store, until I finally found the old guy who knows how to do everything, and knows where everything in the store is.

So, right now, I have the pump, filter, and pressure tank all hooked up to each other, with some garden hose feeding it from a 30 gallon barrel.

The other end of the PEX is just looped back to the barrel for testing.

I still need to borrow a ceramic drill bit from my friend who is a tile-layer. My toilet is against an outside wall, so the existing water line comes up through the floor right behind it.

I plan to drill a second hole through the tile to feed the 1/2 PEX through. Then, I will be able to hook either line water or graywater to the toilet.

One of the segments of pipe is leaking - I must have wrapped the teflon tape the wrong direction or something.

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