In contrast to hard tap water, which is not good for camellias or rhododendrons, you can use rainwater for the whole garden. Depending on the area to be watered, the amount of water required varies. A flower meadow requires much less water than a lawn.
There are various ways of collecting the valuable rainwater:
You can divert the water from the roof into a collector, for example a rain barrel. This should stand in a shaded place and be covered. Note that the containers overflow very quickly if the rainwater is not used for watering at regular intervals.
Another way is to use a cistern or cesspit, from which you can pump the water up using a pump.
When you water, you should generally ensure that you do not water in the hot midday sun. At midday, the sun is at its highest and the water evaporates very quickly. It is therefore best to water in the early morning or late evening. The leaves of the plant should remain as dry as possible, as the leaves may otherwise be burnt. You should also not water your plants too frequently either. If you water less often but more copiously, the plants grow more roots, which anchor themselves in deeper layers. The plant is thus more resistant to dryness.