How to Install a Graywater Irrigation System | This Old House

How to Install a Graywater Irrigation System | This Old House

tell us about gray levels so gray water is water from showers sinks and washing machines it's a little dirty but it's a great source of irrigation water so you get a huge savings on the amount of water you would otherwise need to irrigate and you also get the savings because that water is not going down the drain so you can you don't need to treat it the sewer treatment plant it doesn't need to go into your septic system just an overall great way to save water you can help us today with some of the outside dig and work I'm going to work inside with Julie and get started what we want to do is to install this this is a 3-way diverting valve going to put it right about here now the hose from the washing machine is going to come right to this point and during times when you're using bleach or it's the winter we're going to let that water go the same way it always has from right here this way but if we want to use the irrigation system we're going to turn the handle this way now the water goes to the right and goes out through this pipe it's going to go out through the building down to the irrigation system and your application is perfect here because the washing machine is high enough that it can all work by gravity down this way now this valve it comes as part of the kit you can see all the parts and pieces that the city provides including the clips and the hangers and they even loan the tools to the homeowners to make the installation easy alright Julian we're going to make up these threads but before we do we want some teflon tape on each of these threads all right all right there we go okay okay let's Snug this up with a couple pairs of pliers all right now we can make our connection from the discharge of the washing machine to the bottom port of our diverting valve let me just turn it this way all right so this connection is a standard hose connection with a breeze clamp the valve has threaded connections and we put our transition fittings in and the rest of our work is going to be done in glued PVC all right I just need a piece to get down into the set tub alright and we'll come back and glue these we'll get everything dry fit first alright so that's the set tub now we got to go this way I want to exit the building in the center of this piece of siding I've checked outside for obstructions so there's my mark where I want my hole to be all right so everything has been dry fit there's one more piece I have to install and this is called a mechanical vent or a vacuum breaker now this is a perfect application for your gray water system but it's a perfect potential place what they call a siphon and the siphon needs a short piece of pipe and then a much longer piece of pipe that can pull the water up and out and we don't want any water to leave this washing machine except when the pump is on so this valve would just break the vacuum if there's any suction development all right so here's our discharge from the washing machine we come out through the side of the building we turn vertically down to another elbow right here come across horizontally another elbow and now at this point we're going to transition from our 1-inch PVC to this this is actually one inch high density polyethylene we stick the tubing right over that barbed fitting that's all we got to do now we're just going to get the water to the plants the pipe is all laid and Julien and I talked about you know how much water is coming out per on a weekly basis with her washing machine and then looking at her landscape and how many of the plants we can water so watering half of this side of the yard and half of the other okay and every time we want a water plant we just cut in to the mainline just cut in here and insert a teeth this is a 1 by 1/2 inch T so the main 1 inch line stays and then the outlets go made out a 1/2 inch this side the size is still large enough for lint to pass through so we don't have clogging and then the water continues on so every plant that wants to be watered has one of these strategically placed branches so what's next so next we're going to add the mulch and this is going to filter the gray water so you want the grey water to fall onto this mulch it will filter out lint it'll make it so it doesn't clog up here and act like a sponge don't hold the water it does and then the water can flow through the mulch into other parts of the basin and then just cover it over well we don't want to just cover it over because some roots could grow up into our pipe so we need to protect this part of the system we have two options we can purchase an irrigation valve box and just drill a little hole in it and put that right here and so this is going to be the level of the soil and then we'll fill the rest in with mulch alternatively we could use just a floor just a flowerpot the same thing and recycle it yeah just like cut it a little shorter drill our hole and make uh that's pretty cool alright so now we're gonna fill it in we want the most level to be all the way up yeah we don't want to get that to fill in this mulch okay cover at all level yeah you can Odetta so down here at the ends of the line we don't want to add any plugs or valves or any restrictions it prevents any damage to the washing machine pump now Laurie is done with all of her piping outside so I just want to take you through we've got all of our stuff done now the valve right here is gonna control whether or not you go to the sewer I'll go this way and there's a little label right here on the handle but to make it simpler we also have these signs right here the handle up it's gonna go to the sewer the handle to the sides going out to the garden now the other thing with a grey water system you want to be sure you use the right detergent you want to make sure it's low in sodium low and boron and there's all sorts of choices nowadays so you ready to go I'm ready all right so let's see even get it to discharge here Carly yeah now it's going this way now this way let's go check with Laura come on all right Laura waters on how we doing out here we're doing great it's actually coming out all the outlets look at it there it is all right so you get the right flow everywhere yeah so the system is done done your plants are gonna be happy every time you do the laundry you


  1. This is so AWESOME! Every single time you wash your synthetic clothes, you will get those precious micro-plastics from your nylon / polyester / etc. fabrics thrown on your plants.

  2. Great idea, not to overload the load of nitrogen and phosphorus in the treatment plants, since they do not do the tertiary treatment. Here in Ubatuba / SP / BR, we suffer from the lack of tertiary treatment, since our effluent is discharged into the river, with little flow, and can not self-purify the large quantity of these products in the effluent. Causing the TRANSFORMATION of its waters. I will try to do at home as a way to lessen my collaboration of these pollutants in the effluent of my city !.

  3. 400 amp × 20 on pump 7 = SAT CHEMISTRY EXAM €§©·£ 8,000 amps.10/ 26 / 2018. PST 10:34 am 1/2 drive.

  4. Cool idea, but plants dislike warm/hot water, and all the soap chemicals that your flushing out to water them…also this would never past city building codes…

  5. Don't use this set up on a basement washing machine. The added distance needed to pump water from the basement will cause your pump to wear out prematurely. Your added savings in water just went down the drain when you have to repair your washer or buy a new one. Oops, forgot to turn the valve when I used bleach … there goes your plants. Being green sometimes causes more damage to our environment than it's worth. This is exactly why in some areas gray water can not be used to water ANYTHING.

  6. This grey water system is very simple, ingenious.

    However, from my past experience a garden grey water pond can do do a great job in cleaning the grey water, and they are a great garden landscaping feature.

    So why not use marsh, reeds, or other wetland plants to clean the grey water before watering the garden plants?

  7. What wonderful water conscious City do you live in?  So awesome that they provide the tools to implement!!

  8. Wouldn't the boiling water boil the plants? Plus, one false mistake and you run chlorine to the plants…

  9. Nice. I use washing soap nuts in my washer. They wash pretty well, and I add some bicarbonate too if it's pretty dirty stuff to wash. No unfriendly chemicals (they're nuts, which I crush a little a just put in a bag. It does 3-4 machines of 7kg, for 4-6 nuts, real cheap too!). As we'll have solar water heating soon, and I can put a thermostat behind the washing water entry, then zap out the thermostat in the machine (cold wash), as the nuts work better at 60°, I can use the water pre-heated to get nice frothy, nut-based washing water in the machine. They're available on the net, or even in southern gardens, if you have the time and patience to grow a tree! Thanks for your excellent video (why don't my plumbing tubes go together as well as those do?!?

  10. I thought greywater irrigation systems used ALL the greywater in the house (IE, from the showers and sinks), and filtered it first to remove soap and whatnot. Am i mistaken in this belief, or these more complex systems exist?

  11. I really want to install one of these but our washing machine is in our basement and the water would have to travel up a foot higher than in this video…i wonder if anyone could tell me if it would still work?

  12. why does the flower pot have a big hole in the bottom of it (or it would be the top, since it is turned upside down)?

  13. I have a different system set up where i divert my shower water into a catch basin and it pumps it up to a 275 gallon storage tank. From the storage tank, I water my plants with a hose. I like the looks of that system, but I assume it relies on the pressure from the washing machine. How could I make a system like this that works from the limited pressure of a gravity system?

  14. I will say that is a tempting project. It really is a waste when you think how much grey water you could divert into your lawn and garden from a cities sanitary sewer system. Water bills in most areas are not cheap anymore, because of the cost of maintaining and fixing the old infrastructure.

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