FAQ

Frequently Asked Questions

Can I retrofit my home for greywater irrigation?

Probably not, for the following reasons:

  1. If your home sits on a slab, 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, and it’s not cost effective to tear out wall, and/or floors and pipes just to reuse greywater.
  3. Because a complete greywater system has both a filter unit and underground irrigation, you will have to tear up existing landscape to install the required underground irrigation, and 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 as part of a major remodel.
  2. You were already going to tear into those exact walls and plumbing as part of a major remodel.
  3. You were already going to do either #1 or #2 and extensively remodel your landscape and you need a new irrigation system anyway.

We’ve been designing, installing, and/or supervising the installation of legal full-house greywater irrigation systems for over two decades and have repeatedly seen what 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 the state code, if at all. Most of those supposed “systems” are really just filters of some sort that leave you to try to figure out how to irrigate with the water. Our systems on the other hand do it all, very well, and for a long time. Please explore our website for more information.

Can I use just my clothes washer as a greywater source?

Yes. ReWater’s bag filter system is ideal for a clothes washing machine system with virtually no plumbing hassles. Just move the little J-hook on your clothes washer discharge from the downspout behind your washer over to ReWater’s tank inlet. With ReWater’s irrigation system attached to the pump’s discharge, this inexpensive filter system works as well as our automatic filter but at half the cost. This bag filter package requires you to change a filter bag now and then, which is no big deal but can be messier than some people prefer.

Note that you must attach only a ReWater irrigation package to either type of filter package. This is because our emitters don’t clog from the organic matter that combines with water’s inherent minerals to create “scaling” on the inside of pipe and tubing. In less than 5 years, even using finely filtered greywater, those “scales” flake off and flow into our competitors’ emitters’ orifices and fatally clog them. This is why ReWater has been in the greywater irrigation industry for over 26 years and no other company has been in this industry longer than 5 years. Other companies’ systems keep failing, and they keep going out of business. Please explore our website for more information.

Do I need a pump?

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, which requires a pump. The only time you might get away with not having a pump is if all the irrigated landscape is at a lower elevation than the greywater source and you manage to engineer a gravity-fed system that provides water to plants that aren’t particular about how much water they receive.

Can I use greywater in my existing sprinkler system?

No, for two 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, the post-filtration “scales” in greywater can eventually clog most types of sprinkler heads.

Can I use greywater in my existing drip irrigation system?

Not for very long. Even after you filter greywater, there will still be microscopic solids and the minerals found in the source water supply, which combine 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 highly treated greywater that has been run through an expensive filter costing a fortune in energy and maintenance, or municipally-treated “reclaimed” or “recycled” wastewater that cost the city a fortune to produce.

Can I use greywater to flush toilets?

There is now a section in most state greywater codes that allows treated greywater to be used for toilet flushing. The term “treated” usually means a method that kills 100% of bacteria, virus, coliphage, and other pathogens, removes suspended solids down to 100 microns, and lowers turbidity to 2 NTU. It is an expensive endeavor, and if you live in the West and want a green landscape, you’ll still need to irrigate, so you might as well skip this expense and use your untreated greywater to irrigate your landscaping!

Isn’t greywater too salty for plants?

Greywater is less salty than municipally-treated “reclaimed” or “recycled” wastewater, and isn’t too salty for the vast majority of plants if you simply switch from powdered laundry products to liquids. 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 really 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” to the greywater itself.

Will greywater drown my drought-proof species?

No. Just like with potable water, your drought-proof species won’t drown unless you over-irrigate it. Such vegetation is genetically accustomed to receiving limited amounts of water, but all plant life needs some water throughout the year. Try running your greywater valves just once per week for drought-proof vegetation.

Can I water a lawn with an underground drip system using greywater?

If you are installing a new fescue lawn, you can 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 usually practical where there are large amounts of greywater available and lots of lawn to use that water.

Is greywater irrigation legal?

Yes. Today, most jurisdictions don’t even require permits for clothes washer-only systems, and 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.

In every state but Arizona, a legal greywater irrigation system is a system that uses greywater via an approved underground irrigation method. It does not matter if the water is run through the most expensive treatment method on the planet or ReWater’s relatively inexpensive system, greywater must be used underground.

This is because the public safety and environmental health authorities have determined that greywater is relatively benign. When used underground, it is very safe. With underground irrigation, they don’t have to worry about a treatment system failing and leaving the then-untreated greywater on the surface to contaminate other water.

All the claims about fancy treatment systems that can supposedly clean greywater to this or that “standard” don’t matter—you still have to use greywater in underground irrigation in the vast majority of jurisdictions and you don’t have to treat it first.

How long has ReWater been in the greywater irrigation business?

ReWater has been in the greywater irrigation business since 1990.

In 1992 we successfully sponsored this nation’s first state greywater irrigation law (AB3518). We have 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, as well as countless architects, engineers, contractors, landscape architects, and landscapers, to help thousands of people with their greywater irrigation needs.

You can feel confident when buying the only system that correctly prepares greywater for underground irrigation and uses it in the only underground drip irrigation system that has been proven to work with greywater for over two decades—the ReWater® System.

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