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Gray Water Encounters

Feb. 1, 2012

What's in the tank? This is a rhetorical question given the haphazard tangle of PVC drainage lines leading to the 18-in. opening on top of the 1,000-gal. poly tank. A single 1-in. black well-water pipe led back out of the opening to a makeshift CPVC manifold suspended in place by nylon rope. An expansion tank with a pump switch was nestled between floor joists. Several lines snaked off to serve the home’s toilets and an anti-freeeze faucet. The smell was overwhelming in the crowded basement addition (why it was possible to have such a large tank indoors).

I was there to determine why they were running out of hot water and the owner had led me to the basement.

They told me, "We collect all the gray water from our showers, bath sinks and washing machine to water our garden and flush toilets in our three bathrooms. With three kids, we do lots of laundry!"

They were obviously pleased with their handy work and eager to show off the system. No venting for the tank, which explained the wafting odor reminding me of far too many fetid sump pits where washing machines discharged gray water.

What do you grow in your garden? Turned out they were striving to grow all their vegetables and here in the basement were shelves upon shelves of preserves in mason jars. I politely declined the offer of sending a jar home with me. The hair on the back of my neck was standing on end!

I get the conservation desires, but asked my hosts to do some research regarding pathogens and attempted to explain the fecal choliform bacteria levels in gray water exceed safe levels and that gray water is not supposed to be utilized for watering, or irrigating, vegetables and plants intended for human consumption. They countered with the “fact” that they have been doing this for several years and their family had not suffered any adverse affects.

Fast forward to another encounter with gray water: a new customer who, while having her septic tank inspected (required for most municipalities in my area of Pennsylvania), told the inspector that her washing machine drain terminated at grade. According to her, none of the wash-water discharge ever left her property and she had never seen it have any adverse affect on the yard, which looked like it hadn't seen a mower in decades!

I can clearly remember my grandmother carrying wash-water to pour it onto her flower beds, an early version of gray-water reuse that was quite common.

Plumbing codes have adopted some standards for gray-water systems. The UPC and IPC both have sections dealing with gray-water systems. Piping from the holding tank to flush toilets and/or urinals must be purple (although that is under review and may change) and have bold black lettering clearly identifying it as non-potable. Gray water used for flushing toilets and/or urinals must be dyed, so that end-users can easily identify the non-potable water. Several states have adopted commonsense rules too.

For example, Florida requires the tank be no larger than the average usage within a 72-hour time period. That could have solved the major stink factor associated with the earlier customer's 1,000-gal. storage tank. Plumbing codes, on the other hand, want the storage sized for total exchange every 24 hours. Treatment of the stored gray water is another potential issue.

Water shortages are predicted to worsen over the next decade for many areas in the U.S. DIY gray-water reuse systems are already commonly installed without permits to save money, but also to bypass fees levied from municipal sewage treatment facilities due to using water twice before it is discharged to the sanitary sewer system. Most municipal sewage tratment bills are based upon the gallons of potable water utilized. Gray-water usage offsets the use of potable water for flushing, which reduces the customers’ bills for both water and sewage. Sewage becomes less dilluted, causing treatment costs to rise for the same volume treated. Water usage has been on the decline over the past few decades due to several primary factors, such as smaller families; more efficient appliances (like washing machines); and reduced consumption plumbing fixtures, especially HETs (high efficiency toilets) using 1.28-GPF or less. This has had the unintended consequence of water utilities raising their rates to maintain profits!

Several very important safety issues are often ignored out of ignorance during DIY installations. Professionally installed gray-water systems incorporate three primary points of protection: a potable water-line back flow device installed in the make-up water feed that (in my opinion) should be a testable reduced pressure zone back-flow preventer to protect the potability of the home’s drinking and bathing water. The overflow from the gray-water storage tank will incorporate protection from a black water backup should the sanitary sewer become clogged, and incorporate proper venting to permit free-flow of fresh air, so that foul and harmful odors can be properly rejected from the building.

Our job as licensed plumbers assigned the task of “Protecting the Health of the Nation” is bound to become more, not less, complicated in the coming decade because water conservation in the near future will be at the forefront and incorporate rain- and gray-water systems.

The hot water issue was due to incorrectly (more piping handy-work) twinning two water heaters. As you’ve already surmised, he was looking for free advice.

All Dave Yates material in print and on Contractor's Web site is protected by Copyright 2011. Any reuse of this material (print or electronic) must first have the expressed written permission of Dave Yates and Contractor magazine. Please contact via email at: [email protected].

About the Author

Dave Yates

Dave Yates material in print and on Contractor’s Website is protected by Copyright 2017. Any reuse of this material (print or electronic) must first have the expressed written permission of Dave Yates and Contractor magazine.

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