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Starting Member


Tuesday, May 15th 2018, 4:46pm

What contaminates my potable water?

Two similar scenarios. I'm wondering which scenarios are a real risk to contaminate my potable water supply.

1) I leave a hose connected to the spigot for a month. The other end of the hose is sitting on my lawn. During that month, countless contaminants enter the hose. At some point, I put a sprayer on the end of the hose (the kind that only sprays when "opened" or a trigger is pulled). I turn the water on. Nothing is coming out of the sprayer yet because I haven't opened it. Do the contaminants living in the hose find their way into my potable water supply? I'm assuming so, since I imagine the water doesn't just sit in the hose. It must be moving, right? And has the potential to make its way back into my main supply. (Note: I don't have a backflow device installed anywhere in the system)

2) There's an old PVC pipe I dug up in my backyard. I've traced its path going into my house in the crawl space. I don't see any backflow installed anywhere on the line. It is tied into my potable water supply. I find that this PVC line used to serve a bunch of valves that are part of a sprinkler system (most of which is damaged beyond repair). I bypass the valve assembly, connect the main PVC line directly to one of the sprinkler lines so I have a main line running to the back of my property. I tie some drip irrigation to this line and turn it on, with only a few emitters dripping at 1gph. Similar question as above: There has to be old stale water from the 20+ year old PVC that doesn't flow OUT to the drip, and flows back into my potable supply, right?

(Note: I haven't actually done either of these things, but I wanted to try and understand how this all works before moving forward with any plans)


Supreme Member

Posts: 5,330

Location: Metro NYC


Wednesday, May 16th 2018, 11:18am

The plumbing codes for backflow prevention exist for a reason. Instead of puzzling out scenarios and re-inventing the wheel, just make your plumbing code-compliant. Since most regional plumbing codes consider your sprinkler system water as being toxic (by way of being in contact with the outdoors) you eliminate concerns by making the plumbing code-compliant, and leaving the outside water to stay outside, never again to re-enter the home.

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