Part 2: How to Safely Use Recycled Water For Irrigation

In part 2 of the series on irrigation water, we will discuss the merits and safety requirements for recycled water.

Here are the other articles in this series:

Recycled Water (a.k.a Reclaimed Water)

Recycled water is water treated to remove waste matter attaining a quality that is suitable to use the water again for uses other than potable use. Recycled water is also referred to as reclaimed water. Recycled water is usually distributed on a site using a  “dual plumbed system” which utilizes separate piping systems for recycled water and potable water within a facility and where the recycled water is used for landscaping or fire suppression.

Where Can You Use Recycled Water?

Recycled water used for the surface irrigation of the following shall be a disinfected tertiary recycled water and can be used to irrigate the following:

  • Food crops, including all edible root crops, where the recycled water comes into contact with the edible portion of the crop
  • Parks and playgrounds
  • School yards
  • Residential landscaping
  • Golf courses
  • Cemeteries
  • Freeway landscaping
  • Ornamental nursery stock and sod farms
  • Decorative fountains and water features

What About Runoff?

When using recycled water in the landscape, any irrigation runoff should be contained to the area where recycled water is being used. unless runoff does not pose a public health threat. Additionally, spray or mist from sprinklers should not enter dwellings, outdoor eating areas, or food preparation areas.

Signage Requirements for Recycled Water

Recycled Water signage is required on all sites to inform site visitors not to drink the irrigation water.

Sites that use recycled water must display signage to inform visitors not to drink the irrigation water.

Signage is required for all areas irrigated with recycled water. According to state law, “All use areas where recycled water is used that are accessible to the public shall be posted with signs that are visible to the public, in a size no less than 4 inches high by 8 inches wide, that include the following wording : “RECYCLED WATER – DO NOT DRINK”. Each sign shall display an international symbol similar to that shown in figure” above.

Safety Issues – What Not To Connect To A Recycled Water System

No physical connection is permitted between recycled water and potable water because this is a threat to the public’s health, safety, and welfare. “The portions of the recycled water piping system that are in areas subject to access by the general public shall not include any hose bibbs. Only quick couplers that differ from those used on the potable water system shall be used on the portions of the recycled water piping system in areas subject to public access.”

Why Purple Pipe?

Pipe and fittings used for recycled water must be purple or wrapped in purple mylar tape to distinguish the pipes from the potable water system and reduce the chance of accidental cross-connection. According to the California Plumbing Code, “Tape shall be fabricated of poly(vinyl chloride) with a synthetic rubber adhesive and a clear polypropylene protective coating or approved equal. The tape shall be purple (Pantone color #512) and shall be imprinted in nominal one- half (1/2) inch (12.7 mm) high, black uppercase letters, with the words “CAUTION: RECLAIMED WATER, DO NOT DRINK.” The lettering shall be imprinted in two (2) parallel lines, such that after wrapping the pipe with a one-half (1/2) inch width overlap, one (1) full line of text shall be visible. Wrapping tape is not required for buried PVC pipe manufactured with purple color integral to the plastic and marked on opposite sides to read “CAUTION: RECLAIMED WATER, DO NOT DRINK” in intervals not to exceed three (3) feet (914 mm).” In addition, “all valves, except fixture supply control valves shall be equipped with a locking feature. All mechanical equipment that is appurtenant to the reclaimed water system shall be painted purple to match the Mylar wrapping tape”.

If you see a purple pipe in the landscape, you know that the site uses recycled water.

Can I Put Potable Water Pipes and Recycled Water Pipes in the Same Trench?

No. Recycled water pipes cannot be laid in the same trench as potable water pipes and there must be a 10 foot horizontal separation between the two types of water. Also, recycled water pipes that cross potable water pipes must be buried 12 inches below the potable water piping.

Irrigating With Recycled Water Reduces Potable Water Use

Potable water is a precious resource. Up to 50 percent of residential potable water is used for irrigation. Recycled water is a great way to reuse water that would otherwise go to waste. With proper design and construction, it is completely safe to use reclaimed water for irrigation.


John is a landscape architect who is currently preparing to take the California Supplemental Exam to become licensed in California. He is currently a licensed professional landscape architect in Georgia and Florida. John graduated from California State University, Pomona with a BSLA degree in landscape architecture in 1997 and has extensive practice experience in residential and commercial landscape design.

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