Lee's Liquid Waste Services - Holding Tank Free Advice Have your holding tank cleaned every 6 to 12 months. Install a low-flow shower head in your shower/bath to save water. Repair leaking taps. Spread your washing out over a few days to reduce the load on the greywater sullage absorption / transpiration / aspiration area. Extend the life of your trench and avoid blockages by using lint filters in the laundry - a stocking over the outlet hose will do.Use hot water in the laundry to give a more efficient washDon’t leave taps running unnecessarily, for instance when cleaning teeth.