Grey Water Trial: Flushing Sink Water

grey water

I did something crazy last week.

I asked my husband to cut the plumbing from underneath the bathroom sink so that I can catch the water. The sink now drains directly into a bucket.

It always feels a little rebellious to do things differently than you’re “supposed” to.

My purpose was to use our “grey water” to refill the toilet tank, instead of the tank filling with fresh water from the well. When we switch to solar power, we’ll be hand-pumping our water, so I need to find ways to conserve water in order to reduce our trips to the pump.

We showed the kids the bucket, and explained to them the importance of not letting the water run, and to check the bucket after every use to see how full it is. If it overflows, that wouldn’t be good. The low-flow faucet adapter we installed has cut our sink water usage in half, so that’s been a huge help.

We turned off the water to the toilet and our experiment began.

We’ve been doing this for about a week now, and I’ve made a few surprising discoveries…

1. We don’t use nearly as much water in the sink as I thought we did. I thought for sure we’d fill the bucket at least once a day (as a family of six, with a toddler who loves to play in the sink). I had no clue how much water we used to wash our hands, brush our teeth, etc. It ended up taking us a week to fill a 3 gallon bucket 3/4 full.

It is a good thing that we don’t use as much water as I thought we did in the sink. But it’s not good for my little experiment. 1) We aren’t getting enough grey water from just the sink to flush the toilet as often as we need to (which is not after every use).  2) The water started to stink after sitting in the bucket for a couple of days. I considered putting a few drops of bleach into the bucket, but I don’t want that going into our septic system (and our ground for that matter) and ruining the microorganisms at work in there.

So we ended up having to turn the water back on to the toilet tank so that we could flush it when necessary.

grey water bucket

2. Our “grey water” is more like brown water. I knew my kids got dirty, but I had no idea their hands were so filthy! It never crossed my mind that the water we would be catching would be so nasty. The first time I poured the sink water into the toilet tank I was horrified to find that it was as brown as mud. And then of course every time we would flush the toilet would fill with muddy water.

No good. That is so not gonna work for me.

So now it’s back to the drawing board. I still want to catch our sink water, but I’ll probably use it to water plants instead of filling the toilet tank. Maybe I can use rain water to fill the toilet, and just keep a small bucket in the bathtub to use as needed. I can’t stand the thought of using all of that energy to pump water at the well, just to fill the toilet tank. There’s gotta be a better way.

I’d also like to add a half-gallon jug of sand to the toilet tank, to displace the water and use less per flush. I was checking out a Dual Flush Converter which may be another option to consider as well.

If we were starting over in an off-grid cabin or something, I’m thinking a composting toilet would be very appealing as it doesn’t require water for use.

I’d love to know if you have any experience catching grey water, and have any advice to lend! Ideas??

About Kendra 1035 Articles
A city girl learning to homestead on an acre of land in the country. Wife and homeschooling mother of four. Enjoying life, and everything that has to do with self sufficient living.


  1. I confess, I haven’t read ALL the comments. What I would like to do is CHOOSE what water flushes my toilet. I’m on grid, and I like the way things are, but they seem very wasteful. When I’m rinsing dishes or vegetables, the final rinse is completely clean water, or almost completely clean. I would like to divert that into my toilet, which is one room away. Now I use it for watering indoor plants and my outdoor vegetable garden, but I’d like to be able to press a button and have it divert from my kitchen drain into my toilet flushing system.

  2. Instead of pouring your gray (or brown) water into the toilet tank, try pouring it at pretty high velocity (you don’t need a lot) right into the toilet bowl at the right time. This way, the smelly, dirty water goes away along with the toilet contents, and you are left with a pretty empty bowl. Then, when you wash your hands you can put that water, which will be a little cleaner and not old and smelly, into the bowl to refill. I do most of my flushing this way and never have put anything into the tank. I doubt the dirt and other stuff would be good for the mechanisms in the tank.

  3. At a community in South India we have our laundry area (hand-washing laundry only!) next to a row of toilet stalls (sort of like outhouses but all on the flat rooftop). We have a couple of large barrels to collect the rinse water from everyone’s laundry… then use a small bucket to dip into the barrel and use that water for flushing the toilet. These are hole-in-the floor type toilets, no tank at the back, so this is a great way to flush and save lots of water (otherwise it means using fresh water from the tap in the the stalls). We do have a couple of western-style toilets there, too, and flush these the same way, with the rinse water from a small bucket. Works for us! The large collection barrels do have to get cleaned out periodically, though.

    Also, my cousin in USA (on the grid) uses the water from her de-humidifier in their humid basement to fill her clothes washing machine (just empties the container into the machine anytime it needs emptying, even if not doing laundry same day).

  4. To conserve water in the toilet tank fill a 2 liter bottle with water and put it in the tank…if it leaks it won’t damage your pipes.

    Also, in Japan they sell a pump to pump water from the tub to your laundry machine with an auto shut off function, so you might try searching online for one of those.

  5. My inlaws do this and just pour from the bucket into the toilet when they need to flush. They also use the water from washing leafy greens to flush the toilet or handwashing their clothes for flushing.

  6. To follow up on Kim’s comment of July 2014. In Japan the household plumbing is built so that the family bath water is used later for washing the clothes. But you must understand that the Japanese scrub and rinse themselves before entering the family bath tub which is used as a soaking tub only. All family members use the same bath water. I lived with a modern Japanese family in the early 1980s, and this was standard practice. Also, in Japan all laundry is done using cold water. When American manufacturers entered the country with products for all temperature washing, no one understood what the ads were were about. Water conservation I have always heard is best achieved with a rain barrel. The hippies had a saying, “If it’s yellow, let it mellow. If it’s brown, flush it down.” Saved a lot of water back in the 1960s.

  7. Back when I lived in a farm house with only a huge cistern that collected rain water I had to conserve water all the time but not because of the electric it took to pump it. If we had a long dry spell I could easily run out of water and would either have to pay for a load to be delivered or wait for rain. I did all my laundry for me and my two kids in our re-used bath water. We would all lather in the collected water and all rinsed with clean water as it collected into the tub. At the end of each night after bathes I would empty the tub or at least a portion of the water with a 5 gallon bucket into the wash machine. That grey water was used to wash the dirty clothes we took off just prior to the bath. Clean water was used to rinse the laundry. We never used bar soap so no SCUM ever built up on any surfaces. My laundry always smelled just as fresh as if it were washed in fresh water. Any remaining water in the tub was used to flush the toilet by pouring water into the bowl not the tank, it takes less water to flush that way. BTW, I never ran out of water even in the driest of summers.

  8. Wouldn’t it work if after you used the bathroom you just poured the gray water into the bowl instead? It will take the waste with it and flushes without using the handle. Would that still make the tank full up?

  9. Thinking of your brown water reminds me of Earthship homes. They send the grey water from the sink through a planter and that filters the water for use in the toilet. I am not sure on all details but that is the basics of how that works.

  10. I thought of this before. In the city however it doesn’t save money because sewage is calculated based on water usage not actual sewage created. So it’s the water coming into the house that costs us. Regardless of how much we save or reuse it, we get charged the same. So we didn’t go through with it. I’m not into more work if it’s not saving money. Lol. Catching rainwater does save us money though!! Esp for watering plants and washing things outside, like muddy boots!

    • Mona,

      I’m with you. It has to be worth the trouble if we’re going to do it. I’m not sure I understand how it wouldn’t save you money to save water, though. If you catch 3 gallons of sink water, and pour it into the toilet to flush (especially if you cut off the water supply to the tank), wouldn’t that be 3 gallons less fresh water that your toilet had to have supplied to it from the water company? Maybe I’m wrong?

      • I know this is an old thread but your article was just was I was researching. I live in the city and my water is metered that way. But I have an off grid property I want to move to in NM where water is a real issue. So I started trying different water conservation tricks. The flow to the toilet is shut off at the valve and I flush with dish washing water. A full bucket pured fast and from about two ft up flushes everything down completely. And I lowered my water bill $20.00. That is with just me living here. For a couple or with kids too I’m sure it would make a differene. I stop the tub drain and use that too.

  11. Have you considered changing your toilet out to a composting toilet? You can make your own fertilizer…literally! 🙂

    We are planning on living full time in our RV starting Spring 2016 (boondocking: No water or electricity for weeks at a time), so we have been doing some tests ourselves with how much water we use versus how much our tanks hold. I love the fact that the toilet in our RV uses very LITTLE water – but I would LOVE to replace the toilet with a self composting toilet before we hit the road full-time so that we would only have to worry about dumping our grey water tanks!

    Also, hubby installed a “kill switch” in the shower. I tend to take long hot showers. When we go camping, we now get in and get wet, turn off the water, lather up, turn on the water, rinse quickly and done! This helps conserve A LOT of water!

    This is a link on composting toilets in an RV. I have seen some YouTube videos on them as well.

  12. I’d be thinking an outhouse, especially since you want to go off grid, and you have the acreage to do so. Keep the toilets in the house for whatever, but trying to use a honey bucket or whatnot outside when you can. Even easier to walk outside to do your business when it’s nice out and there’s not 4 feet of snow on the ground. 🙂

  13. I can vouch for rain water! When we lived in Arkansas, we kept a bunch of 5-gallon buckets lined up on the edge of the patio to catch the runoff from the roof. We used those to flush the toilet since we pulled water (oldschool-style) from a well and those things aren’t just unlimited. Only difference is, instead of putting ours in the tank, we’d just pour it directly into the toilet bowl. If you pour it steadily and at a good, quick pace, then the toilet will automatically flush itself.

  14. Kendra, I am thinking shower water. What if you trapped the shower water (as you would if taking a bath) and used one of those fish tank vacuum pump things to transfer it to a bucket or directly to the commode tank? Not a motorized pump; it is one of those hard plastic clear tubes connected to a flexible clear tube or line. Don’t know really what they are called. Anyhoo, it would collect more shower water and you could use it for flushing, watering the garden, and soaking clothes before washing (hey, it’s soapy anyway).

  15. As an avid Motor Home traveler, we love to camp in remote areas, far from any “services” meaning we must conserve water if we don’t want to move the RV every couple days to fill and dump. We use dish water, and the water caught while waiting for the shower to get warm to flush the toilet. This serves two purposes, first conserving water, and adding water to the black tank so it will empty more easily. So, the only gray water in the gray tank is from showers, tooth brushing, etc. It is still enough to adequately flush out the sewer hose after dumping the black tank.

  16. I wanted to try this too, but Hubby wasn’t too keen on the idea. 🙂

    I don’t recommend a container full of sand in your toilet tank though–too much chance for breakage and sand in your pipes! We have a little gizmo called a “Toilet Tank Bank” (looks like a hot water bottle) that goes in the tank.

  17. I have been using Dick’s shower idea for several years now. I get way more water than I can use in a day if I collect all the shower water in a tub of some sort. (But we have more than one bathroom, with one bathroom and many family members it might even out.) My thought is to perhaps redesign the shower so you have a collection tank underneath, that you could hand pump up to flush the toilets. Originally I was thinking to the tank on back, but really you could just use it directly.
    I too plan an outdoor shower, but only for humid summers. In the winter I would keep to showing inside to raise the humidity level and help warm the air. We also line dry our clothes inside in the winter for the same reason. Might not use that much solar power to pump water the three feet or so from shower floor to toilet anyway.

  18. Hi Kendra,
    I’m no expert–but my husband is. He’s a Level 5 wasterwater treatment operational engineer with 20+ years experience. I ran your plan by him. His only concern is that hair, and toothpaste and hand soap “scum” (a professional term, ha ha)will gum up your toilet mechanism. I think my husband would agree with Dick, too. In fact, with our record-setting we are experiencing here, I think we’ll follow Dick’s idea too! Thanks for the post.

  19. what about using essential oils in the water? some have antimicrobial properties … would it be harmful for your plants?

  20. This is one way I save water. When I cook anything in water (potatoes, spaghetti, etc) I drain the water into a bucket and after it cools completely I water my flowers and garden. I also use any leftover water,coffee or unsweeted tea from meals. Oh by the way I had water from cooking potatoes cooling on the porch and the dog enjoyed it.

  21. My solution is to put the 5 gallon bucket under your shower head in your shower. While the water runs until it gets to the proper temperature you will be surprised to see how much water you collect. Dip the water from the heavy 5 gallon bucket with a smaller bucket. Pour that water directly into the toilet bowl not the tank and the toilet will flush. Then refill the toilet bowl again not the tank from the 5 gallon bucket which is sitting on the shower floor. Of course, you will be stepping around the 5 gallon bucket while you shower. That is very clean water which is being wasted otherwise.

    • We use a rectangular 4-5 gallon bucket that doesn’t get in the way when we shower. It fills up while waiting for shower water to heat up. We pour it in the bowl to flush toilet. Thank you for idea of dipping first half out of larger bucket into a smaller bucket to get multiple flushes!

  22. To save water in your toilet tank put a brick in the tank and it uses less water. Recommand reading the book of Humanure by C.J. Henkens. I laugh so much but good ideas and documentative and you don’t use water. The other solution is the outhouse like the Menonites do. pee one side and excrement on the other sideand cover with sawdust. Dede

  23. This is what we do and you are right- it is surprising at your water usage! I feel good putting the water on my plants instead of letting it just go down the drain!

  24. There are a lot of tonics for pest control, healthy veggies and such using urine, soap, beer, cola and other ingredients. I learned a lot of it through Jerry Baker and would recommend his books in a heart beat.
    I’ve thought of saving grey water for watering my veggies but like Rachel found it, there is a lot of it coming from a home over the years. So it would have to be saving just enough to water our garden and not much more. Not sure about kitchen sink water because that could contain grease residue and that wouldn’t be OK for the garden. So I would keep the kitchen sink running to the cesspool.
    If one has a cesspool I would highly recommend adding a monthly treatment to it to extend it’s life. Soap entering a cesspool and it’s drain field breaks down the good enzymes that break down the organic matter in the tank. A monthly treatment of adding the enzymes to the tank is highly beneficial. I learned this the hard way years back.
    I like the idea Bruce had of using rain water runoff to flush a toilet tank. I just got an IBC tank and was wondering how I was going to use it and now I know. If the tank is high enough I can run the water line into the crawl space and up into the tank. I think I’ll test it out first to make sure I have enough pressure to reach the tank that way.


  26. When we put in our homes (trailers) and installed the septic system, my Dad redid the plumbing … only the toilets run into the septic system … all of the sinks and tubs run down to what use to be our goose/duck pond. Life happens – the geese are gone, the pond is nearly full of silt, but we do hope to someday clear the area and turn it into a garden instead.

  27. This is a great idea! I’m an apartment dweller so doing so would likely set my landlord off, but perhaps removing the sink trap temporarily would work. I have a patio with many varieties of herbs and vegetables in containers and have no outside faucet. So I’m forced to use fresh water every few days, roughly 8 gallons, to water them all. Having this as a solution to cutting my water bill would be helpful and it wouldn’t go to waste. My only concern is my fiance with her lotions, sprays, and soaps getting into my plants. I shave in there but I know hair will not harm the plants but perhaps help to keep the rabbits away. I will certainly have to try this.

    • Wendell,

      I would recommend using natural soaps- not only so that you can reuse the water, but also for your health. There’s all kinds of nasty chemicals in cosmetics and toiletries which you shouldn’t be putting on your body. Maybe you can surprise your fiance with some beautiful organic soap and lotion 🙂 I think this would be a great option to help you save on your water bill.

  28. When we moved to our acreage last year we installed a dual flush toilet and I’ve been so pleased with it. This particular one uses a lot less water but also uses more pressure so it can handle bigger “jobs”. Several people can use the toilet before it needs to be flushed and it still uses very little water to get it all down.

  29. Here is an idea. Mount a water container (barrel) on a rack 3′ higher than the toilet on the outside of the house by the bathroom. Run a supply line to the toilet via a new freshly drilled hole through the wall. You can either use a down spout from the roof gutter or fill the water container from your manual well. Since the toilet has a manual float switch for it’s water supply, it would fill as if being supplied from the current household water supply by gravity. You might be able to split the supply line and add a separate faucet to the sink for casual use such as washing hands and such to conserve even more water.

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