Rainwater Tank – Inlet Improvements

In Understanding Tank Water Quality I explained that most tank inlets mix the dirtier incoming water with the cleanest water at the top of the tank.

So what can you do?

Its not as simple as just extending the inlet pipe to the bottom…..The jet of water will create turbulence in the anaerobic zone with the most silt. This will mix this very dirty water with the better quality water higher up the tank, creating problems.

One solution to reduce turbulence is:

  1. Put a ‘T junction at the inlet. (This will allow the falling water to draw in air to further oxygenate the fresh water.)
  2. Install a downpipe to just below the bottom of the tank.
  3. Put two 90 degree bends on the bottom so the flow is directed upwards with the outlet being about 150mm from the bottom. (above the anaerobic zone)

You can get a special fitting for the bottom of the pipe but my solution below will probably be cheaper and just as effective.

Put a ‘T’ at the bottom of the downpipe and have two bends so the flow into the tank from each pipe is half that of the single pipe. (See photo )


To help you pick a tank see Round or Slimline Tanks