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After noticing that some garden hoses carry a warning, "Not to be used for drinking water", I recently switched to one labelled "non-toxic". Does this only mean that the hose is lead-free, or also that it is free of the other chemicals in PVC that are thought to cause cancer? Those of us who grow our crops organically, believe that they are (relatively) uncontaminated. Are we unwittingly introducing harmful chemicals into the food chain, every time we water our fruit and vegetables?

Does anyone know if there has been any research into this, and how safe our hoses are?

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I imaging the "non-toxic" label is in reference to eating the hose rather than toxins getting into the water. For example what would happen if your dog took a fancy to the hose as a new chew toy. –  Rincewind42 Jul 3 '11 at 14:49
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Also the "Not to be used for drinking water" might refer to the pressure rather than toxins. It might simply mean that the pipe hasn't been designed to match your local plumbing codes and so shouldn't be use to pipe drinking water inside your house. –  Rincewind42 Jul 3 '11 at 14:52
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@Man - @win's comment has merit -- I have a drinking water safe hose that mentions it has anti-microbial lining. The instructions on the hose say to make sure that you thoroughly dry it after use, and to avoid introducing any contaminants. I think that both microbe growth and toxic ingredients are the concern. –  bstpierre Jul 3 '11 at 18:23
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I did a google after posting. Apparently the worry is that lead is used to make the pipes. Water that has gone through the hose pipes and been tested came out with lead levels above the safety limits. You're non toxic pipe would have been made without lead. –  Rincewind42 Jul 4 '11 at 0:15
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In 8th grade we also took water samples from everywhere and grew bacteria from them... tap water from taps yielded nothing. There was a plethora from a garden hose. –  Vervious Jul 4 '11 at 17:25
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1 Answer 1

up vote 17 down vote accepted

As Rincewind42 posted in a comment above, one of the reasons for not drinking directly from the hose is that they contain lead. Lead is used as a stabilizer for the PVC in the hose.

This helpful article from the Santa Barbara Independent has a lot of information on hose safety. Another interesting point in that article is that brass hose fittings may contribute to lead contamination.

The advice there -- and that I've seen elsewhere -- is to let water run through the hose for a minute before using it in situations where you really don't want lead contamination, like a children's wading pool or your dog's dish.

If the first flush of water coming out of the hose has 100x the US EPA maximum contaminant level of 0.015 mg/L, then you'd add 1.5 mg/L of lead to your garden if that's where you first spray the hose. So if the first two liters of water are enough to flush out the hose, you'd add 3mg of lead to the garden every time you turn on the hose.

I can't find a definitive reference to maximum soil contamination levels, but several hits on the US EPA website reference a level of 400 ppm as an action level, and I found some mentions of 1000 ppm as a danger level -- don't grow edibles at this level.

So it would seem that if you're:

  • using a hose that has contamination at the high end (100x) of the ones tested by the Independent,
  • always dumping the first bit of water from the hose on the same spot of ground,
  • never add new material (compost, soil, etc) to dilute the old, and
  • growing lettuce (which has a high lead uptake) right on that spot, then
  • you might have contaminated food.

An easy way to know if you've got lead in your soil is to get a soil test. My results came back with a level of 3 ppm, which is below the natural background soil lead level of 7-20 ppm for some midwestern US states.

So I guess I'll continue using a "leaded" hose on the garden, though I may spray the first bit of water onto the lawn instead of the lettuce (see "Lead in Garden Soils and Plants" in the U Minn link above), and I'll use the kitchen sink instead of the hose to rinse off produce.

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Thanks! This is well-researched and very useful. –  Mancuniensis Jul 4 '11 at 12:08
    
@Man - Great question, got me wondering about how bad my hoses are. –  bstpierre Jul 4 '11 at 14:55
    
There are hoses made for recreational vehicles, to fill water tanks for human consumption. They are labeled and usually white. You also have to be careful if you've got warm water flowing through garden hoses. If my horses, dogs, vegetables and myself have to drink or ingest the water, I always use these white hoses. –  stormy Jun 12 at 18:25
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