There are many reasons why a person decides to use a toilet or wash their hands regularly. Embedding a new habit therefore requires multiple approaches. There is evidence that the physical design of and environment in which a toilet or handwashing station is situated plays a role in encouraging long-term, regular use.
To ensure needs are met, users must be consulted and involved throughout the design process. Facilities should be built at convenient locations to encourage people to use them regularly and at the right times. Facilities also need to be easy and pleasant to use.
It is important that they are well maintained, kept clean, and soap, water, toilet paper (if applicable) and other materials needed to use them are replenished as necessary. People tend to like beautiful things and facilities that users consider to be attractive or aspirational will encourage use. Similarly, soap that smells nice can encourage use.
If users are involved in decorating facilities themselves, it may also increase familiarity and acceptability of the facility. Nudges and cues that lead to, point to or emphasise the toilet or handwashing facilities help remind people to use them. For example, to remind people to wash their hands after using the toilet, footsteps or arrows along the path from the toilet to the handwashing facility can be painted.
Colourful hands painted around the handwashing facility can help remind people to use it too. Mirrors and eyes on the wall in front of handwashing stations have helped increase rates of handwashing with soap as people are reminded that others expect them to wash their hands properly as they feel they are being observed.
Placing mirrors above handwashing facilities also has the added benefit of encouraging people to spend longer washing their hands, increasing the likelihood that they wash them thoroughly.
Though this is what the science indicates, creating these acceptable designs alongside nudges and clues can be challenging with limited financial and human resources. However, the principles should be followed as much as possible.