A water tower or elevated water tank is a structure that contains a volume of water, constructed at a height above the ground with pipe connection(s) to a water distribution network.

In this module you will hear about how to keep a water tower in your network for emergency use, and yet still be able to pressure-manage your network at the same time. 

The general purpose of a water tower is to store a volume of water elevated above ground to keep the water in the distribution pipe network pressurised. Water towers can be used to reduce the impact of the water demand variation, acting as a balancing tank. The tank water level will drop during peak flow demands and fill when consumer demand is low.

Technology can significantly improve pressure management in distribution networks, with the help of variable speed drives, pumps, proportional-pressure control and connectivity with network data. 

This means there is no need for the water tower, and water utilities are aware of the benefits in removing a water tower from the network. However, for a municipality, it can be difficult to accept not having a volume of water stored and elevated above ground within the city to cover any eventuality.

This doesn’t have to be the case. A solution is available to retain the water tower for emergency use without the tank affecting the required network pressure, or for limiting the possibility to drop network pressure.

To resolve this, use a small pressure-boosting pump to supply water into the tank and a two-way hydraulically-operated control valve to remove water from the tank. 

This means you can maintain a full water tank with good water quality for emergency use, and at the same time manage pressure in the network.

This is how it works:

The water tower will supply water to the network.

When the water level in the tank is at a lower level, the control valve will close, stopping water from flowing into the network.

The pump will then start, pumping water from the network into the tank.

When the water level in the tank is at a high level, the pump will stop. This cycle repeats, as the control valve will reopen and regulate water flow from the tank into the network without affecting network pressure.

Pressure in the network can be dropped as needed while keeping the tank for emergency use.

If network pressure is too low, the control valve will open to maintain the minimum network pressure. And if network pressure is exceeding the tank pressure, the control valve will open and allow the tank to fill without needing to operate the booster pump.

To find out more about how pressure management can be used for reducing system pressure in the network, see Module 3. 

Let’s recap what we have presented in this module:

• How to keep a water tower in the network for emergency use 

• How to maintain good water quality in the tank 

• How to configure equipment for dropping pressure in the network without the water stored in the water tower affecting this.