Do all restroom trailers have a gray water tank?

No, not all restroom trailers have a gray water tank. The presence of a gray water tank depends on the trailer's design and plumbing configuration.

Gray water tanks are separate holding tanks that collect wastewater from sinks and showers. Trailers with sinks that drain directly into a gray water tank keep that water separate from the black water (toilet waste) in the main holding tank. This separation can simplify waste disposal and reduce odor, as gray water is less contaminated.

Trailers without gray water tanks often have sink drains that feed into the same main holding tank as the toilets. This is common in simpler or older models. It means all waste goes into one tank, which is fine for pumping but can lead to faster tank filling if sinks are used heavily.

For your park event, check the specs carefully. If the trailer listing doesn't mention a gray water tank, assume the sinks drain into the main tank. For a multi-day event with heavy handwashing, a separate gray water tank might be preferable to extend time between service visits. Also, ensure the trailer has adequate fresh water capacity and that your site has level ground, truck access for delivery and pumping, and a power source or generator hookup.

Anyone else dealt with gray water tanks in trailers? What specs did you look for?