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Water quality has become an evergrowing challenge here in Southern California. I don’t know if this is true elsewhere around the country, but in this would-be desert it seems to be getting worse and worse with every passing year — and it keeps showing up in new and different forms.
Water hardness has long been a problem in this area, since the water travels 300-400 miles in open air concrete aqueducts, taking on minerals and concentrating them through evaporation along the way. This hardness is a nuisance, as it calcifies fixture aerators and water heaters, but lately it seems to have created a new, more troublesome side effect.
Keep in mind that I am not a chemist, and I don’t pretend to be one. But, I have had numerous conversations with water specialists on these very issues, and they can be as baffling to them as they are to me.
In recent years in several buildings I have visited, the water hardness shows up in a new and strange fashion. Instead of forming the usual white calcium deposits, the calcium seems to be combining with other impurities in the water, be it iron or other minerals either in the water or coming off the pipe itself, to create a green sludge that collects in faucet aerators and strainer screens. This sludge is predominant on the hot side of the fixtures and valves, so the suggestion is that the calcium that comes out of solution as water is heated is combining with other impurities as noted to create this phenomenon.
It is quite disturbing to the owner of a new multi-million dollar condominium to have green slime on the floor of their tub after draining the bath. Some of you might be thinking, “So soften the water.”
But, that is an imperfect solution. I’ll explain.
Another water quality issue we have here creates pinhole leaks in copper pipe. This has been baffling forensic engineers for many years, but the most commonly held theory today by specialists in this area is as follows.
When copper pipe is formed, it has some inherent impurities. These impurities create very small dissimilar metal microsites. Depending on the impurity it can act as either an anode or cathode in a dielectric reaction, while the copper itself acts as the opposing cathode or anode respectively. As is typical with dissimilar metal dielectric reactions, the anode (either the copper or the impurity, depending) will sacrifice ions to the cathode (the other metal). As it sacrifices ions, the anode is slowly eroded. Once enough anodic erosion occurs, a pinhole leak is formed.
The speed of this dielectric reaction is dependent on water quality, including pH, minerals and other factors. One of these other factors was introduced in the 90s, which is chloramine. As I have written before, the Southern California water utilities switched from chlorine to chloramine as a disinfectant in the 90s because it stays in solution longer and serves better as a disinfected, since it reaches the far end of their distribution systems much more effectively than chlorine. In fact, once introduced, chloramine is very difficult to remove from water. It can be done with charcoal, but it requires a long contact time. A simple charcoal filter will not do the job.
Chloramine is a combination of chlorine and ammonia, and it is the ammonia that is aggressive toward copper. This means wherever the above mentioned micro dielectric events are going on, the chlorine/ammonia combination is going to join the party and accelerate the corrosion — or that’s the commonly held theory anyway.
So, wherever the micro impurities exist in copper pipe there is potential for small dielectric reactions that cause corrosion accelerated by chloramines as well as sodium, pH and other factors. This corrosion eventually creates a pinhole leak, and this, it is theorized, is the basis of the pinhole pipe corrosion problem we have been dealing with in increasing frequency here in SoCal.
Now, the reason I said above that water softening is an imperfect solution in resolving the water hardness and associated green goo is because water softening increases the amount of sodium (or potassium) in the water. So while it does resolve the water hardness problem, it can increase the speed at which pinhole leaks occur, creating a different problem down the road. The more sodium there is in water, the more conductive it is for dielectric reactions. If water softening is utilized, the system should be capable of controlling the softened water at two to three grains of hardness utilizing a slipstream bypass, rather than delivering zero grain water. Zero grain water is more aggressive than water with a few more grains of minerals, so it is more likely to create or support corrosion.
There is a technology that has been around for quite a while that is not often mentioned or utilized, and that is phosphate-based water treatment. In this system, phosphates inhibitors are injected into the water supply to create a micro thin layer of protective film on the inner wall of the pipe. This film protects the pipe from corrosion. The phosphates also reduce calcium scale, improve water color and can reduce lead and copper levels in the water supply