Water conservations negative impact on our infrastructure
When systems thinking isn’t used we end up with unintended consequences. When we intentionally fix one part of the system we can unintentionally negatively impact another part of the system. In this case water conservation and damage to our sewerage infrastructure.
There seems to be a bit of water theme happening at the moment, this one from the awesome website The Conversation. Beware the following post contains material that might affect your breakfast.
“A recent study from Victoria University indicates water-conservation can have unintended consequences for residents and water managers – a problem that is only set to get worse.” according to the authors of the article, Nyoman Marleni and Nittin Muttil.
Basically for sewerage to flow smoothly through the pipes underground it needs to have a certain liquid to solid ratio and once it gets to the sewerage treatment plant it prefers a certain liquid to solid ratio. If there isn’t enough liquid then the sewerage moves more slowly, corrodes pipes and can create great smells – hydrogen sulphide.
So, when we reduce our water consumption (low flow shower heads, water efficient dishwashers, and greywater systems) the amount of waste water compared to waste solid going into the sewers decreases. The amount of waste solid is unaffected by water conservation initiatives – you would have to poo less for that to happen. Anyway, the result of a continued reduction in waste water has been modelled by Victoria University.
What they have found is that greywater systems could potentially reduce the life of the pipes underground from 147 years to just 70 years plus increase the “Hydrogen sulphide levels would increase by 46 ppm which could cause bad headaches, nausea as well as eye and respiratory injuries”.
Rainwater collection doesn’t have as big an impact as it doesn’t directly reduce water use and the waste water component of sewerage. But sewer mining and grey water systems do.
The answer suggested to overcome this problem “smarter sewer pipe design is needed to anticipate the impact of increased water-saving technology use in the network. However, existing sewer pipes need a different technique to overcome issues of sewer odour and corrosion.”
Nnnnooooooooo. What is needed is different thinking. If one action has caused a negative impact in another part of the system, stop the action and work out an alternative. Don’t try and fix the unintended consequence as well.
If distributed greywater and sewer mining systems within the network of the sewer treatment plant cause unintended consequences on the sewer treatment network, don’t allow distributed systems. Rethink the sewer treatment network. Maybe rather than putting in a new sewer infrastructure, keep the existing sewer infrastructure and put in a network recycled water pipe. Same cost but now we have a sewer network that will last its 147 years, a centralized grey water system that will operate more efficiently and more cheaply than distributed grey water systems and it saves water. Or pump the excess treated water back into our water storage dams so it can be re-used.
Yes water conservation is absolutely important but lets not allow the lack of governments investment in our infrastructure force us down the wrong path of continually fixing the unintended consequences of our lack of systems thinking.