access to bathrooms during Covid

It seems I should be able to figure this out, but I can't. The facility where I had volunteered until last March is requiring me to attend a 2-hour meeting next week, in person, outdoors. The facility itself is closed to all except a few staff, including our boss.

We volunteers will not have access to bathrooms or running water. I'll be away from home for about 3 hours, not too bad.

Wouldn't there be public health laws that cover the availability of toilets and running water, or would those laws apply only to paid employees?

Is it unreasonable to expect a toilet and running water?

Maybe it'll be raining. At least you won't have to worry about the running water part.

I don't think it is unreasonable to expect access to a restroom when required to be inside the building.

OSHA requires employers to provide such access. But you might be right that volunteers are not afforded the same privilige.
https://www.osha.gov/restrooms-sanitation

That said, restrooms in public spaces and restaurants and stores are open for use. I would think that restrooms in buildings would start reopening.