Saturday, January 10, 2009

So you want to buy a house?...part 5-acidity

Last installment I talked about well water and a non-issue issue (water hardness), so what is the major issue facing home owners with well water? Acidity of the water, pH primarily, but there is a lot more to it and that is why I write.
First, the prevalence of acid water is close to 50% in this area, but the main issue with acid water is its aggressiveness to the water pipes in the home and that runs only about 33%. A neutral pH is 7.0 and the average in the area tends to 6.6 (the lower the number, the more acid).
So acid water in of itself is not a health concern, we drink coffee and soda and many other things which are significantly more acid, but because it flows through copper piping, it can corrode the piping, creating pinhole leaks over time and increasing the level of copper to above levels that affect health.
The good news is most acid water conditions do not bring copper to that level and amounts of copper below 1.3 mg/L (milligrams per liter, which is about a quart) are not bad for you (you are suppose to get 1.0 mg per day).
Next, testing for pH is both easy (you stick a calibrated pH probe and measure) and problematic.
Why problematic? One of the main components of acidity in well water is carbon dioxide, a gas and it comes out of the water easily, even in a closed container. The recommended testing time is within 15 minutes. Now that presents a serious problem for most home inspectors who have contracts with labs in Danbury or even Norwalk, there is no way they can get the sample to the lab in that time period and many batch their inspections and bring the samples late, putting them in a holding refridgerator at the lab so they can be tested in the morning. The value of the pH goes to neutral over time. So many pH values are not reported correctly.
The actual problems an acid pH will cause is a combination of many factors, alkalinity (measure of Carbonate), Calcium, chloride and other disolved solids. Some labs will do a TDS (total dissolved solids) with the pH to calculate the corrossivity of the water, others will do an alkalinity and calcium hardness with pH to do the same. The corrossivity calculation will show if the water has the potential to cause problems for your water piping and that is the most important issue, otherwise the number for pH is meaningless.
There are other factors which will cause pipes to corrode that are not related to the water quality at all and that has to do wqith electrolysis due to poor or improper grounding of the home electrical system. This will almost always bring the copper measurements in the water to unhealthy levels, but correction can only be found using an electrician who understands the word (many do not).
My next installment will be on other metals which may cause various problems.
Post a Comment