Collecting rainwater may be your garden's answer to the summer drought but still water attracts bacteria. This fantastic Water Butt Cleaner is just the ticket to cleanse and freshen your collected rainwater. This Water Butt Cleaner is a natural, biodegradable, seaweed based liquid, which restores water's natural balance through the stimulation of naturally occurring micro-organisms present in rainwater, making it fresh and ready for watering your plants. It also has the added benefit of deodorising your water butt! Two capfuls (approx 50ml) will treat 100 litres of water. Apply weekly until water is clear and odour free. 1 Litre.