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

2. Enter the capacity to overflow of the bath(s) into column (a) and the quantity of shower(s) into column (b). N.B. this capacity should exclude displacement as this has already been included in the use factor for baths.

3. Where multiple baths are specified with various capacities, use a separate row to input the capacity (a) and quantity (b) of each design specification.

4. Click ‘Calculate’ to calculate the average capacity to overflow and the weighted average capacity to overflow. The larger of these two values will be carried forward to the ‘Water Calculator’ (column (1).

Notes: The weighted average capacity to overflow is calculated as:

= Maximum capacity to overflow (litres) x 0.7

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

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