Size the collection tank and surface based on the 1:1:1 ratio. For every 1 square foot of garden, you need 1 gallon of storage and 1 square foot of rooftop. Larger tank or collection surface is better, more resilient. But the 1:1:1 ratio is good.

Prefilters can be self-cleaning (Intewa Plurafit or Leafeater) or a basket filter in the manway of the tank. Basket filters are most popular, but they require cleaning several times in the fall, and at least once in the spring.

Many people try to use IBC "tote" containers for rainwater collection. While they are cheap, many people have problems with algae and sediment clogging them (see bottom photo). Mosquitoes, too. You need to filter the water before it enters the tank, and a tank material that blocks the light.

Many of our community garden projects use the Grundfos SBA pump. It might be undersized for automatic irrigation systems, or when using more than 2-3 hoses simultaneously. But it is self-contained, automatic, and winterizing is a simple as unplugging an electrical cord.