LOW-IMPACT SYSTEMS Materials Compost toilets can be made of wood, fiberglass, brick, or con- crete block. The choice depends more on cost, workability, availabil- ity, and builder experience than it does on material suitability. All these materials are suitable, recognizing that all but fiberglass must be coated with a waterproof sealant. Chutes may be made of bot- tomless wastepaper baskets, flower pots or barrels, or concrete storm drains. Regular toilet seats work well, but a weather-stripped lid that encloses the whole seat should be installed. Stovepipe makes a fine vent, and there is no need for the elaborate heat shield- ing when stoves are vented through ceilings and roofs. A 15-watt fan should be sufficient to provide circulation. Construction Because of the danger of fires (which have occurred with early- model heated compost toilets), home construction of small cham- bers which will require supplemental heat is not recommended. There are many designs which can be constructed by the home- owner and construction details of a particular design will not be given here. A few general construction tips should be observed. 1. Caulk and seal all joints, including connections to vent openings. Weather-strip all doors, portholes, and lids. 2. Install a cap (or wind turbine) on top of the vent stack and make sure the top of the stack is higher than any part of the roof within 10 ft of the stack. If no fan is used, the stack should be much higher-up to 15 ft above the roof. Construct the vault and waterproof the interior. Be sure to coat all interior surfaces, including baffles and edges of openings. Coat the underside of the vault top with a waterproofing material, then apply caulking to the top edges of the vault sides before fastening the top. Also, it's much easier to add the "starter" composting materials (see next section) before the top is fixed in place. 4. Note: A black interior will attract far fewer insects than a light color. 202 ONSITE WASTEWATER DISPOSAL Operation and Maintenance Directions for start-