Yes pool water is healthy. Changing and toilet rooms are a separate issue though that need to be managed.
However the bigger problem is that in most public pools in Australia that they are a very big energy consumer (water, heating, filtration, salt chlorination or the various other ways of sterilisation used at large pools in Australia, and then there is the air within the buildings too (HVAC running costs for as air temperature and humidity both need to be controlled. ). In many municipalities their aquatic centres are their biggest consumer of power by far. There is a real science, including data science, to managing pools to keep costs down and achieving the right water quality and when I conduct sessions on this topic it is always one of the more popular ones.
Opening a public pool for 20 people will not be viable at many swimming pools.
Those with outdoor lap pools may just choose to open them, or one of them. Operational costs can be a lot less as these may not be heated, plus avoid the HVAC costs.
If they do open for only 20 people at a time larger centres will be burning cash. The smaller the pool, the more likely that they would be viable to reopen.