1. If there will also be bath(s) in the new dwelling, tick the box next to ‘Are there any baths present?’

2. Enter the flow rate into column (a) and the quantity into column (b).

3. Where showers with varying flow rates are specified, use a separate row to input the flow rate (a) and quantity (b) of each design specification.

4. Click ‘Calculate’ to calculate the average flow rate and the weighted average flow rate. The larger of these 2 values will be carried forward to the ‘Water Calculator’.

Notes: The weighted average flow rate is calculated as:

= Maximum flow rate (litres/min) x 0.7

Where the average flow rate is lower than the weighted average flow rate, the weighted average is entered into the ‘Water Calculator’. This is so that where the average flow rate is significantly lower than the maximum flow rate specified, the calculation limits the flow rate that can be assumed.]

Different use factors are assumed for showers according to whether or not bath(s) are also present in the dwelling.