Pipe up: Off-network developments

“We will see more and more buildings disconnecting or partially disconnecting from water and sewerage networks”

When I think about networks, two main topics come into my head. One of these is off-network developments.

I think these will become an increasingly hot topic in the next few years. Water neutrality and off-network buildings have been discussed for a while, but two developments in Sydney are actually doing it. One Central Park is a mixed commercial and residential development of 3,000 homes and 65,000m2 of offices and retail, and it is totally self-sufficient in water. It catches rainwater and reuses water via a membrane bioreactor in the basement. It is so successful it exports water and is off-grid in terms of sewerage and water supply.

An even bigger development is under way in Barangaroo, which will harvest rainwater, recycle all its grey and black water and when additional water is required it will mine water from Sydney’s sewers. Its recycling plant will produce 1 megalitre a day and this means that it will be able to export water.

However, these net positive water developments still require some access to the utility networks. Because this type of model is frightening Sydney Water, it is attempting to restructure its billing to make going off-grid uneconomical. But this economic warfare is bound to fail because it will mean that future Sydney developments will just disconnect completely.

I believe that over the next decade we will see more and more buildings disconnecting or partially disconnecting from water and sewerage networks.

The issue for network management will be to manage low demand and low flows, and changes in patterns of water demand and the composition of waste streams. If these issues are considered now and water companies work with developers, or water companies actually manage off-grid water and sewerage solutions, then they will have control of their destiny.

It is time that water companies started to manage whole water systems outside of their own networks. This means they will have to: get better data on the state of networks and on dynamic flow conditions; start using thermal sensors in sewers to check where water is coming from; start considering allowing other people to put water into their supply networks; and consider shared ownership of networks.

All of this will be accelerated by competition, but it means that network managers will have to expand their definition of what a network is, because we are moving quickly beyond pipes and sewers into buildings and catchments.