Step 1 - Check how much rainfall there is in your area

England 880 Wales 1494 Scotland 1651 N Ireland 1223
England and Wales 955 England N 1024 England S 804 Scotland N 1718
Scotland E 1299 Scotland W 1931 England E & NE 819 England NW 1307
Midlands 784 East Anglia 591 England SW & Wales S 1325 England SE & S 836

Or for a more specific figure, visit the Met Office website.
mm

Step 2 - Enter your collection area

The collection area is just the footprint of your property (we deal with the roof pitch later)

Please enter your dimensions below:
Main Building   m   m
Garage   m   m
Outhouse   m   m

Step 3 - Roof Pitch

The roof pitch has a bearing on how much water runs off and how much goes down the downpipes.

Refer to the chart below and enter your "Drainage Co-efficient" as appropriate.

Grass Roof 0.3
Flat Roof 0.6
Standard Pitched Roof 0.8

Step 4 - Filter Efficiency

Filters do not always give 100% water yield. Ones that self clean often loose between 5-10%

Unless you know otherwise please leave the box below as 95%
%

Your Tank Size Recommendation

Once you have completed the entire form, click the button below to calculate your recommended tank size

Your required tank size is: