Anyone know if EPDM rubber is acceptable for potable water?

[Ethan Brush]

Not exactly sure which topic this should go under.....Ive got a shallow dug well and I want to seal off the concrete block work casing down to about 5 feet. At first I was going to get a poly water tank, cut the bottom off and stick it upside down over the top, but to get one here (would need to be about 60" diameter) got up around the $800 range with freight. I have some EPDM rubber here I could use. Anyone know if that is suitable for potable water? I did a bunch of internet searching, and there seems to be sort of a consensus that it is fine, but nothing from any sources I really trust. Seems like this would be a definite known thing from rainwater catchment systems. There are expansion tanks, but as far as I can tell those use butyl rubber for the diaphragm or bladder. Wikipedia says this:

As a roofing membrane it does not pollute the run-off rainwater (which is of vital importance for rainwater harvesting).

But has a "citation needed" after it LOL.

 

[Reach4]

I know that EPDM is used as the diaphragm material for some water well pressure tanks. So the material itself is OK. However it may have to have approvals or testing for the particular use.

In the case of wells, the states have rules. I suspect concrete and bentonite clay may be the only approved materials. So the question is not whether it is technological suitable but whether it is allowed.

In the pressure tank arena, the EPDM is not as good a butyl rubber, because there is less air diffusion through butyl. This might mean that you need to check your precharge air pressure every year with EPDM vs every few years with butyl. Many tanks also use a blend of butyl and EPDM. This air diffusion would not be a factor for lining ponds or stopping water at wells.

 

[Sponsor]

 

[Valveman]

Not sure it will work, but EPDM is certainly fine for potable water.

 

[Ethan Brush]

Thanks guys. I am certainly no plastics expert, but another thing I am concerned about is can we make a blanket statement about a given plastic (or synthetic rubber)? For example there are of course polyethylenes for potable water, but I am not sure ALL polyethylenes are acceptable for potable water. I assume "polyethylene" is a fairly broad term and there could be certain variable ingredients such as colorants, plasticizers, etc. which may or may not make it potable. Just a thought.

Anyway, Ill post a picture shortly. I had thought of using bentonite, but that stuff is quite a hassle to get mixed up and applied, plus I dont have any handy.

 

[LLigetfa]

Not sure it will work, but EPDM is certainly fine for potable water.

Don't be so quick as not all EDPM is the same. EDPM roofing might have anti-fungal properties. When I purchased it for a roofing job, it came with a warning not to use it as a fish pond liner. There is EPDM made specifically for fish ponds.

Decades ago, I had a shallow dug well with 48 inch concrete rings. I daylighted the top two rings and wrapped it in multiple layers of poly to keep surface water out and to mitigate frost jacking.

 

[Ethan Brush]

Here is a picture. Obviously the block wasnt the best choice for this and it should have been those concrete well liners all the way (I added that one), but its what I have so Im trying to fix it up. I patched all the gaps in the block with mortar. The blocks do have the cores filled with concrete. I am going to backfill the whole thing with mason sand, and then dirt for the last couple feet. I like the idea of sealing the top 5 feet to prevent surface water from getting in and forcing any water through the sand filter, hence my idea to use the rubber.

 

[LLigetfa]

I patched all the gaps in the block with mortar.

How deep does the frost go in New York? The surface is very irregular so if it is subject to frost, it can grab it and jack it.

 

[Ethan Brush]

Decades ago, I had a shallow dug well with 48 inch concrete rings. I daylighted the top two rings and wrapped it in multiple layers of poly to keep surface water out and to mitigate frost jacking.

I did consider doing that, just wrapping the top half in some poly sheeting. I also have some of that foundation dimple sheet membrane which is HDPE. But the spec sheet says "Can be ordered non-polluting for drinking water" and what I have was not ordered "non polluting, so who knows...

 

[Ethan Brush]

How deep does the frost go in New York? The surface is very irregular so if it is subject to frost, it can grab it and jack it.

They say 4 feet, but that area doest appear to freeze due to the continuous ground water.

 

[Sylvan]

Check with local area code inspectors

https://up.codes/viewer/new_york/ipc-2015/chapter/6/water-supply-and-distribution#6

 

[Ethan Brush]

I did find this from the EPA:
(sorry its hard to read. Basically it just says rubber membrane has no pollutants of concern and is suitable for all uses)