Frequently Asked Question

These FAQs and answers are compiled from ReWater’s experience with greywater irrigation since 1990.

PROBABLY NOT, for the following reasons:

  1. If your home sits on a slab, unless you’re completely off the grid, it’s almost never cost effective to cut into the slab just to capture greywater.
  2. If you have a raised foundation, but the master shower or other highly productive greywater source is on the top floor, that water is almost certainly already connected to a toilet and turned into sewage before the pipe goes down the wall. It’s usually considered not cost effective to tear out walls and/or floors and pipes just to reuse greywater.
  3. Because a complete, legal greywater system requires both a filter unit and underground irrigation, you will have to tear up existing landscape to install the required underground irrigation. That’s usually not considered cost effective if your irrigation system was already working properly.

Caveats: Some unique situations mitigate those factors, such as…

  1. You were already going to cut into your slab at the exact location as needed to divert your greywater as part of a major remodel, AND you are going to extensively remodel your landscape, AND you need a new irrigation system.
  2. You were already going to tear into those exact walls and exact plumbing as part of a major remodel, AND extensively remodel your landscape, AND you need a new irrigation system.

We’ve been designing, installing, and/or supervising the installation of legal full-house greywater irrigation systems for over three decades. We have repeatedly seen the real obstacles you’ll be facing to legally retrofit a full-house system. If you can access your greywater sources, and you do need a new irrigation system, then our extremely robust, time-proven systems are for you.

Note that while there are lots of “greywater systems” on the internet, none of them have been proven to work very long in underground irrigation as required by every state but Arizona. Most of those “systems” are just some sort of filter that leaves you trying to figure out how to irrigate with the water.

ReWater’s systems, on the other hand, capture, filter, and irrigate with the water, using a sophisticated but user-friendly controller, that can automatically supplement with city water when you go away on vacation. Please explore our website for more information.

YES. You won’t get as much water as from the whole house, but you will get water. There are virtually no plumbing hassles when using only clothes washer water. Take the little J-hook on the discharge tube from your clothes washer currently on the downspout behind your washer and move it over to ReWater’s tank inlet, or a pipe draining into that inlet. From there, attach ReWater’s filter unit.

Note that you must attach only a ReWater irrigation package to a ReWater filter package. This is because our emitters don’t clog from the organic matter that combines with greywater’s inherent minerals to create “scaling” on the inside of pipe and tubing. In 2-5 years, even using finely filtered greywater, those “scales” flake off and flow into our competitors’ emitters’ orifices and fatally clog them. ReWater has been in the greywater irrigation industry since 1990 because all our components are made for untreated greywater. Other companies’ components keep failing, so they keep going out of business. Please explore our website for more information.

YES. You need a pump if you want to irrigate uniformly, irrigate different sizes of plants or plants with differing irrigation needs, push water across flat land or uphill, or enjoy any type of automation. A drip system does not work without pressurization. Pressure requires a pump.

NEVER, for three reasons. First, it’s illegal in every state to spray untreated greywater into the air due to the possibility of human pathogens becoming ingested by somebody walking by at the time, or those pathogens running off into surface waters for possible human ingestion. Second, old greywater on the surface stinks. At best, it smells like dirty laundry. At worse, it might pond and turn putrid. (In underground drip, you can’t smell it.) And third, the post-filtration “scales” in greywater will eventually clog most types of sprinkler heads.

NOT FOR LONG. Even after you filter untreated greywater, there are still microscopic solids and the minerals found in the source water. All that stuff combines to form what are called “scales” on the insides of pipes, valves, and tubing. These scales flow downstream and clog conventional drip emitters of every make. It’s not a matter of if they will clog, but when they will clog.

If somebody tells you differently, ask them to show you an untreated greywater drip irrigation system that has been working properly for longer than 5 years that isn’t a ReWater system. They can’t. What they will invariably show you is either treated greywater from an extremely expensive filter costing a fortune in energy and maintenance, or municipally-treated “reclaimed” i.e. “recycled” wastewater that cost the city a fortune to produce.

There is now a section in some state greywater codes that allows treated greywater to be used for toilet flushing or sprinklers. The term “treated” means a method that kills 100% of bacteria, virus, coliphage, and other pathogens, and removes suspended solids down to 100 microns. Treatment is an expensive endeavor.

Worse, the new test for treatment systems, NSF 350, did not use real greywater and greywater systems certified under NSF350 don’t work with real greywater. You might as well skip this expensive experiment and use your untreated greywater to irrigate your landscaping!

NOl. Greywater is less salty than municipally-treated “reclaimed” a.k.a. “recycled” wastewater, and isn’t too salty for the vast majority of plants. Simply switch from powdered laundry products to liquids as you must for modern HE (high efficiency) machines anyway. Powdered laundry products are full of salts. They rely on salt’s negative ions to loosen debris from fabrics, whereas liquids rely on enzymes to loosen debris. It doesn’t matter which liquid you switch to — any liquid is better than powder.

For acid-loving plants (that probably should be grown in the tropics rather than the arid West), you might want to add gypsum to the soil or “liquid gypsum” periodically to the greywater itself.

NO. Just like with potable water, your drought-proof species won’t drown unless you over-irrigate them. Such vegetation is genetically accustomed to receiving little water during the hot months, but all plant life needs some water throughout the year. Try running your greywater valves in drought-proof zones just once a week. To keep from losing the greywater that is produced daily, alternate the drought-proof zone valves so the greywater is going to a different valve or valves each day.

YES. If installing a new fescue lawn, install a matrix of ReWater’s underground tubing and proprietary emitters beneath it. Lay fescue sod on top of it, and surface irrigate that sod to establish the lawn’s roots in the soil. Once those roots are established, they will use the greywater being applied underground and no longer require surface irrigation. This has been done numerous times and is most practical where there are large amounts of greywater available and lots of lawn to use that water.

YES. Today, most jurisdictions don’t even require permits for clothes washer-only systems. Some jurisdictions don’t require permits for systems that don’t exceed a certain daily volume of greywater (usually about 250 gallons per day).

Permits for ReWater’s systems are obtainable in every jurisdiction in California and in most Western states. Various local permit jurisdictions have various permit processes, but with a ReWater system and a “legal site” (which usually means a site with sufficient landscape to irrigate) you can almost certainly obtain a permit. We offer a code compliance form with each purchased system to expedite the permit process.

A “legal” greywater irrigation system is a system that uses greywater via an approved underground irrigation method (except in Arizona). It does not matter if the water is run through the most expensive filter method on the planet or ReWater’s relatively inexpensive filter system, greywater must be used underground (exception is when a NSF 350 certified system is used, but those have proven to fail.)

When used underground, untreated greywater is very safe. With underground irrigation, you don’t have to worry about a treatment system failing and leaving untreated greywater on the surface for kids to play in, animals to drink, or to contaminate other water sources.

ReWater has been in the greywater irrigation business since 1990.

In 1992 we successfully sponsored this nation’s first state greywater irrigation law (AB3518) right here in California. We tirelessly worked with numerous legislatures and virtually every local, regional, and state building, water, and environmental health agency and NGO in California concerned about building safety, water, and wastewater impacts.

We have since worked with countless architects, engineers, contractors, landscape architects, and landscapers to help thousands of people with their greywater irrigation needs.

With a ReWater® System, you have the only system that correctly prepares greywater and uses it in the only underground drip irrigation system that has been proven to work with greywater for over three decades.