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  • Drinking water safe materials?

    Hi everyone,

    I want to make an adapter for my faucet/tap so I can use my new table top water filter but I'm having a bit trouble deciding on the right stock to use due to lead content etc.

    Would lead free brass be OK? or would something like Delrin be best?

    Its a very simple project but I have spent hours researching materials and I'm still lacking definitive answers so any help would be appreciated.

    Cheers,

  • #2
    Even leaded brass is fine.
    The lead almost immediately forms lead oxide
    and lead oxide is not harmful to humans.
    The trouble with Flint Michigan is the treatment plant
    put the wring chemicals in the water, and it dissolved
    the lead oxide, and the pure lead was leaching off
    and poisoning people.

    -Doozer
    DZER

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    • #3
      Delrin would work fine, but is somewhat sensitive to chlorine. Acetal would be a good choice, easy to work with and should last forever.
      Kansas City area

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      • #4
        NSF is the group that specifies materials for food usage in the US.

        According to their material standard you would be ok with any 200, 300, or 400 grade stainless or any copper, brass, or bronze with a lead content under 8% (so long as the only exposure is potable water).

        Plastics can be a bit trickier, since depending on the exact type of plastic there are concerns about chemicals leaching out. For that you would need to look at the FD&C act to check on a exact material, but generally I think you'd be safe with any pure nylon, abs, or pvc materials.

        If it was me I'd probably just go with a 360 brass - it meets the criteria, easy to machine, will hold threads better than delrin in the long run, and is used by many manufacturers of similar fittings.
        Cayuga, Ontario, Canada

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        • #5
          Originally posted by Tom S View Post
          According to their material standard you would be ok with any 200, 300, or 400 grade stainless or any copper, brass, or bronze with a lead content under 8% (so long as the only exposure is potable water).
          I read recently from here: https://www.copper.org/applications/...water_act.html

          The most recent change involves the 2011 Reduction of Lead in Drinking Water Act, which amended section 1417 of the SDWA and became effective on January 4, 2014. This new act made the following changes:
          1. Redefine lead free in SDWA Section 1417(d) to:
            • lower the maximum lead content of the wetted surfaces of plumbing products such as pipes, pipe fittings, plumbing fittings and fixtures from 8.0% to a weighted average of 0.25%;
          Does that change what you would recommend? or would you still be happy with 360 brass?

          Last edited by stevejigsaw; 10-07-2021, 11:38 AM. Reason: Grammar fix

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          • #6
            I'm thinking of going with C693 brass: https://www.onlinemetals.com/en/buy/brass-round-bar-693

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            • #7
              Originally posted by stevejigsaw View Post

              I read recently from here: https://www.copper.org/applications/...water_act.html

              Does that change what you would recommend? or would you still be happy with 360 brass?
              I'd still be happy with the 360. Its got around a 3% lead content and meets the standard that was acceptable for years, and if you applied the 'weighted average' system to you whole house plumbing would most likely easily stay under the .25% wetted area (I'm assuming this is just a small adapter, not a large section of brass pipe or anything).
              Cayuga, Ontario, Canada

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              • #8
                Originally posted by stevejigsaw View Post
                I'm thinking of going with C693 brass: https://www.onlinemetals.com/en/buy/brass-round-bar-693
                Nothing wrong with that either.
                Cayuga, Ontario, Canada

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                • #9
                  Originally posted by Toolguy View Post
                  Delrin would work fine, but is somewhat sensitive to chlorine. Acetal would be a good choice, easy to work with and should last forever.
                  Delrin is Acetal. Delrin is a trade name for acetal homopolymer (iirc). Acetal is also available in copolymer.

                  I would go with brass or stainless steel, mostly depending on what was on the shelf…

                  Dave
                  Just south of Sudspumpwater UK

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                  • #10
                    The copolymer is the better choice.
                    Kansas City area

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                    • #11
                      I would have said acetal too, but not knowing which polymer would be most suitable. Thanks Toolguy for clearing that up. Of course I would now ask why copolymer would be better?
                      I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-

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                      • #12
                        Originally posted by darryl View Post
                        Of course I would now ask why copolymer would be better?
                        Me, too. A backgrounder here: https://weeklypellet.com/2016/08/19/...s-homopolymer/

                        And here: https://www.hardiepolymers.com/knowl...-or-copolymer/

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                        • #13
                          They didn't actually add anything to the water in Flint. What they did was switch to a different source for the water that was very acidic, and then didn't correct the pH so it leached the lead from the pipes. RO water will do the same thing at a pH of 7 because it is so pure.

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                          • #14
                            PH of water is supposed to be held at around 9 or 9.5 to minimize the solubility of lead. If they did not even do that, they really screwed up (but we knew that).
                            2730

                            Keep eye on ball.
                            Hashim Khan

                            Everything not impossible is compulsory

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                            • #15
                              The copolymer isn't sensitive to chlorine like the homopolymer. Most tapwater is chlorinated.
                              Kansas City area

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