Mean Daily Max Temp (deg C)
Jan Feb March April May June July Aug Sept Oct Nov Dec
27.3 27.3 23.9 18.6 13.9 10.7 9.6 11.3 14.4 17.8 21.6 25.1
Mean Daily Min Temp (deg C)
Jan Feb March April May June July Aug Sept Oct Nov Dec
13.4 13.8 11.4 7.9 5.3 3.4 2.7 3.4 5.0 7.1 9.3 11.6
Mean Rainfall (mm)
Jan Feb March April May June July Aug Sept Oct Nov Dec
48.3 48.7 60.2 67.0 92.4 110.7 108.8 106.1 92.2 91.3 66.2 59.3

The above table was taken from this site and I have recorded it to refer to while I am researching. This week I have been looking into water supply and am happy to see reasonable steady levels of average rainfall for the area.  The other figures on the site were from 2006 so I am assuming the rainfall are too… I know they have had a few dry years of late so I am certainly taking it as a guide only.

The table below comes from this site & I have added his to give a snap shot of what one group says we use:

Wastewater source Total wastewater Total grey water
% Total Litres/day % Total Litres/day
Toilet 32 186
Hand basin 5 28 8 28
Bath/shower 33 193 54 193
Kitchen 7 44
Laundry 23 135 38 135
Total 100 586 100 356

Now, assuming we are putting in composting toilets – yes we’ll need two as we would like an ensuite and yes, this may seem excessive to those who believe that a sustainable house should be small but we want one, we’ve never had one & the whole house is only about 20 squares anyway -we’ll immediately save 186 litres a day or over 67,000 litres a year (obviously these figures vary from site to site).

If we continue to use Table II we can assume that our family will need 400L of water each day (i.e. 586-186 for toilet).

This site gives you an idea of what you may use on a daily basis & will calculate how large a tank you may need to store water.  However, being very conservative (probably wasteful) I calculate from this site that a family of 4 COULD use up to 722L per day WITHOUT flushing toilets – that’s worked out on the basis that there will be 3 showers a day, 1 bath, 1 load of washing, 1 cycle of the dishwasher, 4 tooth brushings & the estimated 24hr cooking amount (note – this will be our water supply so I want to over estimate).  Based on this site calculations & assuming it can be 2 months between rain, we’d need to have a tank with a 46,000L capacity.  If we go by Table II we need a tank of 32,000L capacity.

These guys sell tanks with a 46,000L capacity so I have emailed them for some prices – i think we’d end up getting 2 of these tanks so there is plenty of reserve.  On top of tanks for the household we will need water for fire fighting & we are going to need pumps.  So much to think about & that’s not including where to place all the tanks!  There are lots of places to buy tanks so I think we’ll just go into a few and ask what they recommend!

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