Where filters are installed in hard to reach tanks, we recommend using the backflushing nozzle set PR-100-RSDS. The backflushing nozzle is installed in the PURAIN rainwater filter behind the sieve. For this purpose, it is passed through the filter drain pipe and then through the existing hole and finally is fixed from the outside by means of a locknut. It is then connected to a water pipe with the help of a garden hose plug-in coupling. Now, flushing can be done manually using a hand valve or automatically using a timer controlled valve.