Three Way Diverter Valves
aka three port valves, 3-way valves, L-port valves

For Greywater Systems

Summary: Special 3-way valves used to divert water between alternate destinations.

If you landed on this page searching for good deals on pool or spa valves, that's what the larger valves were originally manufactured for and they will work perfectly in that application.


add to cart $39 — Three-Way Diverter Valve 1" (brass)
$59 — Three-Way Diverter Valve 1.5-2" (plastic)

Three way diverter valves are recommended for greywater systems:

  1. To divert water to a septic system or sewer (if you want to launder with bleach, irrigation is not needed, or it's frozen out there...)
  2. To switch greywater between alternate irrigation zones in the garden

The only systems I design without diverter valves are for the simplest homes which don't have a septic or sewer to divert to.

Three way valves work better than the alternatives (two ball valves, movable pipe sections...) in that they are more likely to be used properly and that they don't clog as readily.


1"Threaded 3Way L-Port Brass Ball Valve for Washing Machines

This high quality brass three port valve is recommended for laundry-only systems, in particular,

the Laundry to Landscape  system. One-inch female pipe thread. Note: unlike the valve below, the inlet can only be the leg of the tee (the part pointing down in the image at right), with the water diverting to the either side of the run.

add to cart $39 — Three-Way Diverter Valve 1" (brass)


Three way valve installed

Three Port Diverter Valve for 1.5" or 2" House Plumbing

gray water diverter valveThese three port valves are the greywater industry standard. Besides being well-made, lifetime-lubricated, and guaranteed never to leak or break, they have the huge advantage that you can unscrew the face plate and turn it to make any of the three ports the "inlet."

The face plate can also be removed for cleaning out the valve or nearby clog.

They last a long time. We suggest you use "no-hub connectors"   if there is space, or glue them with silicone sealer if there is not, so they can be reused if you want to change the geometry of your plumbing in the future.

The valves can be operated remotely and/or automatically with a motor actuator (we don't handle these; they are quite expensive).

The valve fits two pipe sizes; one on the inside (1.5") and one on the outside (2") of the hubs.


$59 — Three-Way Diverter Valve 1.5-2" (plastic)

More details and instructions


Why these valves are superior to ball valves in a greywater application

We had a customer write to us,

Customer: "What I don’t like about the valve is the large cavity and jagged edges within which will be a potential for debris to build up and cause clogs. I think I am better off with a simple 2" ball valve (yes more work to splice two valves in) which present a smooth diameter wall to the flow. I am a mechanical engineer, I know a thing or two about flow. I am afraid to take a chance with your valve."

Oasis: "All of us thought that about those valves. However, empirical data trumps theory, and in this case none of us have ever seen a clog at these valves in twenty years of field experience. This came up for the city of Tucson, and I just checked a month ago with the guy who has put in more of these for greywater than any of us in the country, and he's never seen a clog at these valves, either. Makes no sense to me, but there's 20 years of in the field experience that contradicts what I, and everyone thinks would happen. (Moreover, if it does clog, you can unscrew the face of and clear it.)

Experience has not been so kind to dual ball valves installations. The dead end run tends to clog with a plug of crud which won't easily dislodge when the valve is moved. This is an experiment that has been replicated many times. If one chooses to go this route, I suggest making it dissasembleable and writing up your results after a few years of use (it takes a while for the crud plugs to form--most diverter valves are left in the same position for weeks or months at a time). I don't think anyone has ever quantified this. There is a pool valve called an Ortega valve which is the best of both worlds, (a smooth diverter valve) but it only works in one geometry and I don't think I've ever seen them in a greywater system, only on the shelf.

It's kind of unnerving to not have a single failure; this is like the only part of greywater systems that doesn't clog. It makes me wonder if the turbulence might actually be helping to mobilize stuff, or some other apparently 2nd order effect that's actually dominating."

Why you shouldn't buy plastic valves (or anything made of PVC, for that matter)

The plastic diverter valves above are the best solution currently available for greywater diversion in 1.5 or 2" pipe. However, they are made of PVC, a bad plastic.

Before clicking the "buy" button, make sure your system is designed to use as little resources as possible in its use and maintenance, including using as little plastic, as little bad plastic, and as few valves as possible.

The typical system uses at most three of these valves, one for the kitchen sink (yes, this this is legal only in Arizona so far, but the rules will catch up elsewhere before the house falls down), and one for the rest of the plumbing, and a one-inch brass valve from the laundry.

Why are we offering these if they are made of bad plastic? Well, they are the least of evils in many contexts that have conventional plumbing (which, in the West, is actually ABS, slightly better than PVC).

It is possible to make greywater valves of a better material (and a better design). If you or someone you know has a plastics manufacturing plant, please contact us for a design for better valves. The minute there is a more ecological valve, we'll drop these.

Also, consider that the whole idea of diverting greywater "elsewhere" is suspect. If it is too toxic to put on your garden, where exactly is it OK to put it? A more fundamental solution is to not buy anything that can't go on the garden, then put it all on the garden full time; no diverter valves.

For a way to accomplish this and avoid 90% of the plastic and all the PVC use in a system, check out our information on Radical Plumbing in Create an Oasis with Grey Water (book).

Information on the evils of PVC

PVC: A Health Hazard From Production through Disposal by Paul Goettlich

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Keywords: three-way valve, 3-way valve, 3 port valve, 3 way valve, jandy valve, hayward valve, waterways valve, pentair valve, diverter valve, greywater diverter valve, graywater, grey water, gray water, two inch, 2", 1.5" 4717, 4715 • Copyright © Art Ludwig 1997–2018 • Content Use Policy