Monday, November 3, 2008

How to collect grey water (and flush your toilet with it)

As I mentioned in my recent water bill post, I have started collecting my shower greywater and am using it to flush the toilet.

Here's how I do it:

1. Collect the shower warm up water

2. Dump the shower warm up water in a bucket

* At this point you can do one of two things:
  1. leave it at that and only use this water - doing this means that you can put the water directly in your toilet tank as follows: next time you flush the toilet, empty this water in the tank as it is filling. I don't do this because it sounds like it takes a lot of coordination, plus I only collect 1.5 litres of warm-up water per shower. Or

  2. you can keep going and collect the grey water too:

3. Put the plug in the shower to stop the water draining out

4. Shower. Navy style.

5. Collect the soapy shower water. Yes. That's my shower water. What, you thought I'd waster a shower's worth of water for this demo? :-) Don't be grossed out - its only soapy water.

6. Dump this water in the bucket along with the other water

Now you have your water collected, here's how you use it...unlike the shower warm up water, it is not recommended that you put grey water in your toilet tank. The soapy residue can gum up the working parts. Also if you have a fancy toilet, you know, like a dual flush one, you might have a warranty which would probably get voided if you put soapy water in the tank. So what do you do?

It's the easiest thing ever.

You won't believe it.

If you pour the greywater, from the bucket, directly into the toilet bowl, the toilet will.....flush. For reals folks. Takes more water than the toilet would normally use to flush (at least half the bucket) however the net effect is zero as this water would have gone down the drain anyway in the shower.

So there you have it - the totally low tech, no cost way to recycle some of your greywater.

If you are more of a fan of high tech, this system, sounds interesting (bonus - its a Canadian company - based in Montreal). It uses chlorine though.

And here's another low tech option for capturing greywater.

You can also use greywater to irrigate your garden. Check out the water purification/irrigation system in Earthships.

Oh and one last thing. If you are going to capture your greywater and don't plan on treating it (like with the bucket method), you should use the water within a day. After that, the water can grow bacteria and will generally be unhealthy to have around. If you haven't used it within a day, it's probably best to dump it out.


Theresa said...

I know I was totally enthralled when I first dumped a bucket of water down the toilet bowl and it actually flushed! I save a lot of water this way. Sometimes I will even save my sink tap warm up water too.

We are on a cistern system here, which needs an electric pump to get the water from the cistern into the house. And, we live in the country and there are fairly regular power outages. In short - no electricity = no flushed toilets. So having a bucket of water with two extra flushes in it is a little extra piece of mind as well....

Adam said...

I like your idea, but I'm curious to know if you're aware of any toilets that can use soapy (hand soap or detergent) water without it being a risk to the inner components? Caroma toilets used in Australia can use some soapy water but it probably shouldn't be in excessive amounts. the Japanese have been using this method as well for a long time too...

I'm doing this for my final year design project, so any help would be worth a degree =)

Green Grrl said...

Hey Adam,

I've seen those tank-top sinks before and think they are pretty cool. Great for small spaces for sure. I wonder though how many hand washes it would take to fill the tank. I try to use as little water as possible so I'm thinking it would take me a while to fill the tank that way.

Interesting about Caroma. Our toilet is a dual flush Caroma. Good to know that I could put some soapy water in it's tank if I wanted and it would be ok. I have to admit I haven't heard of any (other) toilets that can use soapy water in the tank.

It would be cool if you could somehow easily transfer shower water to the toilet tank and perhaps filter it in situ to get rid of the soapy residue.

Then the only issue would be the bacteria that can be in handwashing water and shower water. That's another reason why I prefer dumping the water directly in the bowl. Otherwise I might feel the need to clean/disinfect the inside of the toilet tank on a regular basis (and cleaning is not high on my fav things to do!)

Hope that helps a little.

Any chance you'll be sharing the results of your final year project? I'd be interested to see it. :)

Liz said...

I was planning on reusing shower water to flush the toilet, but when I told my mom, she said that her mom used to do the same thing during droughts, but that they ended up ruining the plumbing system because the soap residue collected in the pipes (not the tank) and eventually clogged them. Do you think perhaps the soaps these days are more easily dissolvable so it wouldn't happen, or do we need to be careful of this?


Anonymous said...

Hi Liz, I wonder if there was a different reason for your grandmother's clogged pipes because if she didn't reuse the shower water it would have gone down the shower drain anyways. If those pipes never clogged it is surprising that the toilet drain pipe clogged because it would have been exposed to less total shower water over time.

Just a thought because I have some memories from when I was young where one detail stands out and I attribute that as the entire reason for the story but after talking to other family members that were there we realize it's not