Jane Dodds wants local councils to be given more money to help keep public toilets open.
The Mid and West Wales MS asked at the Senedd about the support available to councils.
She said communities across Wales are having to assume responsibility for operating and maintaining public toilets.
Ms Dodds said: “Local authorities try their best to provide limited funding, but they are severely constrained by ever-tightening budgets.
“The lack of public toilets and the unavailability of them being open at particular hours means that this affects not only our own residents but visitors as well.
“Public toilets are central pieces of infrastructure, particularly for older people.”
During the Senedd session, Ms Dodds referenced the situation in Rhayader, where the town council took over the operation of public toilets in 2015, “only to have all funding support withdrawn in the subsequent years.”
Ms Dodds asked Finance Secretary, Rebecca Evans, what she can do to help community groups and local councils operate and maintain these “essential public facilities”.
Ms Evans said local authorities' average funding increase for this year is 3.3 per cent, and each of them will need to balance service delivery against available funding.