Garden-only system are designed to be as simple as possible, so that they can be retrofitted without the need to interfere significantly with existing drainage, plumbing and interior decoration.
In the typical example illustrated, water is being collected from a single down-pipe which will fill the tank during the winter months, ready for use during summer dry spells. Use of a filter inserted into the drain-pipe further reduces the need to interfere with existing drainage runs.
Where required, an above-ground storage tank can be substituted for the underground tank depicted; conversely on new-build or retro-fit projects, and in particular where the system is part of the SuDS arrangements for the site, the harvested rainwater can be collected from multiple down-pipes and an-tank filter used.
Relevant points to note when ordering a garden-only system, are:
- The stored water is quite suitable for irrigation purposes, but it is non-potable and ingestion or inhalation should therefore be avoided.
- The usual pattern of usage is to collect water throughout the winter months, and use it in the summer; this means that usually even the largest storage tank will fill during the summer months from only one down-pipe, so there is usually no need to over-complicate the collection arrangements
- It is recommended that users employ the stored water during dry spells in the most effective way possible, which usually means avoiding the use of inefficient oscillating sprays; however, as a guide to the tank size you require, such sprays generally dispense around 500-litres of water per hour
- If you plan to use the water in association with a reticulated (“leaky-hose”) system, please discuss with Freerain beforehand, as measures need to be taken to avoid such systems shortening the life of the pump
- And finally, we do not recommend the cost and complexity of installing a mains-water top-up device to garden-only systems, as they may not keep pace during topping-up (due to pressure-loss across the air-gap) with the rate at which water is being used. It adds un-necessary cost and complexity to the system, wastes electricity by recycling mains-water through the system once the harvested rainwater has all been used*. It therefore makes practical sense to have a second, mains-fed, bib-tap for use when the harvested rainwater supply is exhausted.
*This consideration does not apply to full domestic systems which are designed to take into account the completely different operating cycle of collecting water every time it rains, and using water every time a toilet is flushed