Measure the length and width of the top of the Porta Potty or other chemical toilet. Make a note of the dimensions. Chemical toilet sizes vary but are typically about 14 inches wide and 15 inches long.
Purchase a toilet seat riser of an appropriate size, checking that the dimensions fit those of your chemical toilet. A riser is a piece of molded polyurethane that can be placed on the rim of a lavatory when the seat is lifted. The riser provides a higher seat for users, effectively raising the height of the toilet. This item of kit is also known as a toilet raising block. Many models are available and can be found in shops that cater for people with disabilities or mobility problems or from online distributors.
Lift the seat of the chemical toilet and place the riser on the rim. No tools are needed to fit the riser and it can be removed when it is no longer required. Typically, the riser will raise the effective height of the toilet by about 4 1/2 inches, depending upon the model chosen.
Clean the riser with soapy water or disinfectant as necessary.
