Copper piping and cathodic protection?

[Ken Fabian]

We rely on collected rainwater for household water. We get some copper staining via the cold water taps but not the hot water. The hot water system has a sacrificial (cathodic?) inclusion - I think it is zinc.

I was thinking of adding a piece of zinc into the rainwater tank to stop what is slow corrosion of the copper pipework - and prevent that staining. Changing pH by periodically adding chemicals does not appeal - and would require regular water testing and treatment. Anyone here that could advise on whether a piece of zinc (perhaps hanging inside the water tank) would work? Or offer suggestions?

 

[Baluncore]

Or offer suggestions?

The lowest cost and longest lasting solution is to replace metal pipes with black poly pipe, made from high density polyethylene, HDPE.

 

[Ken Fabian]

The lowest cost and longest lasting solution is to replace metal pipes with black poly pipe, made from high density polyethylene, HDPE.

I am a big fan of avoiding unnecessary expenses and extending the working life of the existing infrastructure, which still works fine, seems like a very reasonable approach. It seems likely to be a lot easier and cheaper.

I think my question is whether the sacrificial cathode needs to be in contact with the copper pipework to work? Some more reading suggest that it does and hanging zinc in the water tank won't do it; probably lazy of me to put the question here.

I need some way to do so without constricting the flow - I am thinking of adding a dead end tee-join with a removable end and put a piece of zinc in there.

 

[Baluncore]

I am a big fan of avoiding unnecessary expenses and extending the working life of the existing infrastructure, which still works fine, seems like a very reasonable approach. It seems likely to be a lot easier and cheaper.

Less work, but the scrap value of the copper would pay for the poly pipe and fittings needed.

What is the roof made from?
What are the rainwater tanks made from?
Does your rainwater contain sulphur from acid rain?
Does your electrical system use the copper pipes as a ground?

You might install plastic couplings or plastic sections, between sections of copper pipe, so that corrosion currents cannot circulate between the different metals at different ends of the system.

You might use a short copper pipe section, with larger diameter, to house a zinc sacrificial electrode.