Meanwhile, these arrived yesterday. Each tank has a capacity of 2000 litres (500 gallons). One will catch the water off the deck and the other will take water from the house roof. The tank on the left is slightly higher than the other and will overflow into the lower one. Whilst this will be nowhere near enough to keep a garden the size of ours alive without rain, every little drop helps. The tank stands have been quite a family affair - I posted photos of the grandchildren doing their bit a few weeks ago.