Are you finding black sludge on your fixtures?

Cathal Walsh
Environmental Blogger
Friday, 26th April 2019
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Water coming out of the end of a kitchen tap

At some point you may notice a layer of black slime developing on your faucets and several other fixtures around your house like your shower head. This looks pretty sinister doesn’t it?  You’ll be pleasantly surprised to know that this more than likely is not shown to be detrimental to human health.

Sometimes a black tint in the water may be caused by oxidising pipes or the dissolving of rubber seals in your water system. The main and most prevalent cause of this however is manganese.  The black slime is oxidised manganese and the bacteria that feed off of it. You’ll be happy to hear that the WHO has concluded that manganese is not harmful to humans in the levels it may be found in drinking water.  They do however recommend that it be maintained to a level of 0.05mg/l in drinking water.

This issue seems to be a lot more prevalent in cases with individuals who get their water from private wells. In the case of finding black slime on your fixtures it is always good to ascertain an exact reading for the level of manganese in your water. The only way to do this is to get a sample of the water and get it tested at an accredited lab.

The way in which you may treat the levels of oxidised manganese in water differs depending on where your water source comes from.

If you get your water from a private well then the answer is most commonly a process of oxidation and filtration.  In this process a chemical is added to convert the dissolved manganese in the water  into a solid particle.  Once oxidized the manganese particles can then be easily filtered out of the water. Chlorine is the chemical which is most commonly used as an oxidant in this process however it is not uncommon to hear of potassium permanganate or hydrogen peroxide being used instead.

If you experience this and you have mains water however, then chlorination will not be effective for you. This is because in the case of mains water the high levels of manganese are from the city water and the water is contaminated before it reaches your residence. Several treatment options here are available.  These options include ion exchange systems , sequestering and oxidising filter systems.

If you happen to find black sludge in your fixtures, it is always best to purchase a water test and send it to an accredited lab for testing.

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