Q: Smelly brown water is coming through my rainwater harvesting system. I have been advised to add chlorine to the underground tank. What do you think?

A: Whilst that will work. It's not the ideal solution. Adding chlorine will probably solve the problem in the short term, but realistically you need to find out why it occurred. If you use the water for your washing machine adding chlorine won't do your clothes any good, and it's not that great for your garden either.

The ideal solution would be:

1. Check the gutters that feed the rainwater tank. Clear/clean any organic matter, there may have been a dead bird for example. If there were any of these, then the chances are, that was the problem.

2. Then check and clean your filters. Again, any sign of organic matter would suggest that this is the source of the problem. Remember, you do need to check your filters regularly.

3. Empty and clean the rainwater tank. This largely depends upon whether you've found the problem or not, the level of smelly water coming out, and what you use the water for. If for example, you use it for toilets/washing machine, then this would really be a must. However, if you only use it for garden irrigation, then it will probably correct itself (if the source of the problem were organic matter in the gutters or filters) over time.

Ultimately, you need to find the source of the problem. Remember, the tank in a rainwater harvesting system is pretty much a sealed unit, and it must have been contaminated in some way. Therefore, chances are, the cause will be found in 1 & 2.

Photo by Tabitha Hawk

About the author: Barry Nutley is co-founder and director of Viridis Energie Consultants

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