How to check water pipe earthing?

[Timmy_T]

Hi, I've posted this in the plumbing section, without any reply, so thought I'd try here instead!

We've had major problems with well water and manganese filters in an old cottage, and the water engineers have suggested that maybe the water pipes are not adequately earthed. They seem to think that the whole water system may be acting as a huge battery and causing copper from the pipes to be ingested into the water. This ends up turning my wife's hair green, turning the water blue when we add soap, no soapy suds in the washing up bowl and making the washing smell awful.

The water is pumped from a well (via filters) in a blue plastic pipe, no mains water, and we've a mixture of copper and plastic pipe around the house. I've been around and cannot find one earth to a water pipe, no earth to the gas pipe, and no earth spikes outside that I can see (but thats not to say that they're not hidden away somewhere!).

The only visable earthing I can see is around the meter and consumer unit (meter dated 2003, consumer unit installed 2006). There are 3 earth cables running into a junction box with one earth cable running out into a wall, and that's as far as I can see.

How can I test that the water pipes are adequately earthed?

Is this a plausible theory or just clutching at straws?

 

[PrenticeBoyofDerry]

Do you have any documentation/certificates that state the earthing arrangement on them?
To test for main bonding continuity you need a meter that can test continuity, a simple multimeter can do this, you may also need a wander lead (long conductive cable) that can be connected to your service pipe work if there is a distance between MET of CU and service pipe work, the end to end reading of the wander lead should be deducted from the low ohms reading of your continuity between MET and service pipe.
The earth conductor connection you will need an earth loop impedance test, a special meter that will test your earth fault loop.
But saying that, I cannot see that this is the reason behind your pipe work corrosion.
To prevent this you need to have a sacrificial anode in place, they are usually made of magnesium.

A galvanic anode is the main component of a galvanic cathodic protection (CP) system used to protect buried or submerged metal structures from corrosion.
They are made from a metal alloy with a more "active" voltage (more negative electrochemical potential) than the metal of the structure. The difference in potential between the two metals means that the galvanic anode corrodes, so that the anode material is consumed in preference to the structure.
The loss (or sacrifice) of the anode material gives rise to the alternative name of sacrificial anode.

 

[bernardgreen]

This is possibly one situation where the pipe work MUST be earthed to the ground. Bonding a metal pipe to an electrical "earth" derived from the neutral of the incoming mains supply will create a small but not insignificant potential difference between the pipe and the water in the well. Current flowing in the water will create electrolysis effects, how much will depend on how is dissolved in the water in the well.

What sort of pump is being used ? If it is electric and the pump chamber is metal and earthed to the electrical earth it might be there where the problem is.

A plastic pump feeding direct and only to a plastic storage tank might help to reduce the problem. Then gravity or pump feed from that tank using the tank a galvanic separation point.

 

[PrenticeBoyofDerry]

For the electrolytic action to cause corrosion, as bernardgreen has indicated you will need two dissimilar metals in circuit, and the water in the pipes could be creating this circuit.
So ideally any filters or pumps would be better if in plastic.
The affect could also be at any metallic storage tanks or cylinders.

 

[Timmy_T]

Thanks for that.

Would an electrician be able to check if the earth is sufficient, or seeing as it's in connection with the water pipes would it be a plumbers job?

 

[RF Lighting]

Definately a job for an electrician.

 

[stillp]

At the risk of asking the obvious, do you have some evidence that the well water is free of copper before it gets into your pipes?

 

[Timmy_T]

At the risk of asking the obvious, do you have some evidence that the well water is free of copper before it gets into your pipes?

Oh yes! This has been on going for some time, with regular water testing. the initial problem was put down to the manganese in the water, so a £2k manganese filter system was installed, but we are still having problems so other avenues are being investigated, such as this!