Mains water requires energy to pump and purify, the chemicals involved are bad for you, your garden, and the environment in general, not only in their use but their production and transportation. Harvest and store rainwater to water your garden, wash your bicycle, fill your birdbath.
I have a 1000 litre cube. It was pretty cheap to buy and when it was delivered it was installed onto the downpipe. Unfortunately it gets empty after a fortnight of watering the garden in summer when there is no rain, and in winter it stays full all the time when no watering is needed, but in spring and autumn it comes into it's own.
We're building anew and will be installing two 50,000 L tanks onsite, eventually with a grey water re-use system to feed used water from vanities, shower and sinks (not kitchen sink mind) to the garden.
Please be careful when collecting water. Some places have laws preventing the collection of rainwater. For example, some states, here in the United States ban rainwater collection not just because they want to control people but because it is a serious health issue. Safety can extend a lot farther than someones own back yard.
West Nile virus never use to exist here in the united states. Now it does. It has an opportunity to spead faster when humans are careless. Mosquitoes get the virus from by biting infected birds. Then the mosquito bites a person. It can be painful and fatal for the person who has been bitten.