Treatment of drinking water - Corroded water pipes: should they be replaced?
Most homes in Luxembourg built since the beginning of the twentieth century are equipped with galvanized steel pipes. A thin layer of zinc serves as a sacrificial protection. This protective mechanism implies that the zinc is partially dissolved in time and that the pipes are no longer protected. After the disappearance of zinc, the steel will begin to corrode and give the water a yellowish tint, then brownish.
The lifetime of the pipes is very variable and depends on several factors. Some galvanized steel pipes are still in very good condition after more than half a century, others in very bad condition after only a few months.
Replace drinking water pipes
In general, the first thought when one discovers that drinking water pipes are corroded, is that they must be replaced. However, they are usually inside walls and floors, making replacement very expensive. When a complete renovation is planned, such a replacement may be considered. But what to do in other situations?
Is it dangerous for your health?
The water is not necessarily yellowish or brown when the pipes corrode. But at the latest when the morning, the first jets are colored, there is a doubt about the drinkability of the water. The coloring of the water is mainly due to the iron oxide resulting from the corrosion. However, iron oxide does not have a negative impact on health.
In galvanized steel pipes before 1970 may also be traces of lead. In this case, there is a real danger to health, especially that of children, and a control of the level of lead in water is recommended.
Identify the causes of corrosion
Sometimes, some elements that contribute or cause corrosion are easy to identify and once controlled, can significantly reduce corrosion:
• Excess carbon dioxide in drinking water due to poorly regulated or inappropriate anti-lime treatments (CO2 injection, softeners, etc.)
• Corrosion related to solid particles, such as sand seeds, metal chips or corrosion particles. Installing a prefilter reduces these risks.
• Absence of land or an inoperative land: in order to eliminate stray currents, it is imperative that the pipes be connected to the earth. Often, the ground is too dry, the oxidized cables or the contacts are not tight.
Other sources of corrosions are more difficult to identify and manage:
• Corrosion due to water composition, eg high levels of chlorites or sulphates, or an excess of free CO2.
• Corrosion induced by microorganisms.
Solutions to avoid pipe replacement
Once the sources of corrosion have been identified and, if possible, eliminated, several solutions are available to protect and preserve the weakened water pipes. Over the years, certain techniques have demonstrated their effectiveness and the replacement of the pipes can be avoided in many cases.
However, each case requires careful analysis before determining the appropriate solution (s). With the appropriate treatment, the colored water gradually disappears, the incrustations disappear and give way to a homogeneous protective layer without the use of chemicals. The water system remains healthy and protected without impeding the quality of drinking water.