1300 364 858

Blue green staining on your bathroom basin, toilets, bath or showers is a tell tale sign that you have a problem. And if you don’t attend to it early, you could be up for massive bills to repair water leaks!

For those living off rainwater tank supply, there has been more evidence in recent years of problems of corrosion in the water pipes of houses. The problem appears to be related to the increased number of polyurethane water tanks, and the increase of acidity in normal rainwater

A neutral pH level for water is 7.0. But normal rainwater has a pH of about 5.6. This means that rainwater is naturally acidic.

Concrete water tanks can help balance acidic water naturally through the lime that is used in making the tanks. However, with more polyurethane water tanks and metal roofs collecting rainwater, more and more problems are occurring with the copper lines as the acidic water is not being neutralised.

Blue green stains on your ceramic basins, showers and bathtubs are the first sign that you have a problem with the pH balance of your water. The acidic water is eating away at the copper pipes (soft metal corrosion). And this can end up causing leaks in the piping as well, which can lead to much bigger problems.


A variety of factors contribute towards making water corrosive.

What this basically means is that metal pipes and fittings are going to be corroded to some degree. The extent of corrosion will greatly depend on how aggressive the water is and the type of metal it is in contact with. “Light” metals such as mild steel and copper will be most at risk; stainless steel the least.

Brass (copper, zinc and lead) is at risk to corrosion and will leach the metals back into the water. This can occur in a matter of hours and the ‘first flush’ portion of water from a brass tap may contain high concentrations of dissolved metals such as copper and lead, which are of health significance. If the water in a dwelling is known to be corrosive, water should always be run off from taps for a few seconds before being used for consumption.

The blue green staining on ceramics in the house are signs that copper (either from the pipework throughout the house, or from the hot water cylinder), is stripped off by the corrosive water. In all metals, this will eventually lead to pinhole corrosion (referred to as pitting), which will leak and require repair or replacement.

While blue green staining is the initial identification that a problem might occur, confirmation can be made with a water analysis. A complete analysis of the water will help identify if your water supply is aggressive or corrosive.

When pH is below 7.4, that is becomes acidic, it becomes corrosive. Aggressive water can be buffered by high Alkalinity and Hardness, however another effect of low pH is to increase the solubility of calcium carbonate, which is the main compound associated with the formation of protective scale deposits on pipes and fittings. Other factors that can make water aggressive are chloride, sulphates and dissolved oxygen.

Other dissolved gases that contribute to the corrosion of metals are carbon dioxide and hydrogen sulphide. Carbon dioxide does not directly cause a corrosive reaction, but it reacts with water to form carbonic acid, which in turn lowers pH. Similar to carbon dioxide, hydrogen sulphide does not by itself cause corrosion. Sulfide deposits will promote galvanic attack, characterized by localized pitting, due to the electrical potential that exists between sulphide and metal.

So determining the overall aggressiveness of waters can be somewhat complicated and there have been a number of formulas developed to predict the tendency of waters to be corrosive (or scale forming).

The extent of aggressiveness in your water supply will be explained in a water report using the physical results and the above indices as a guide. Pristine Water Systems will provide solutions with every water analysis conducted.

If you have any signs of blue green staining on your ceramics, then it could pay to call your local Pristine Water Systems operator to inspect. We can assist in providing water analysis and testing to determine the actual cause of the problem, and subsequently provide solutions.

You can call us today to book an assessment of your water supply system, or contact us online.

Having the right filtration system will save your pipework and ceramic staining!

Calcite filters are the most popular solution, but you need to consider other issues such as sediment build-up and potential for bacteria (from faecal matter and animal carcasses) when defining the right solution for your needs.

Contact Us

Contact Pristine Water Systems today if you have any questions about your water tank systems.