Wedding reception is 6 hours. Do we need porta potties serviced during?

You do not need a mid-event service visit for your wedding. A standard unit and an ADA-compliant unit have a combined holding tank capacity that will handle 100 guests for six hours.

The industry guideline for events starts at about one unit per 50 to 75 people for a four-hour event. You have two units for 100 people, which is a good ratio. The factors that increase usage are alcohol, a full meal, and duration. Even with those factors, the tanks are unlikely to fill in six hours. A service visit during the event is disruptive; the vacuum truck is loud and the area will be in use. The rental company may suggest it as an upsell or for a much larger crowd. Good truck access does not change the need. The units will hold up fine. A post-event service is standard. The main factor driving the cost of a service visit is the labor and fuel for the truck run, not the actual pumping time. Save the money and skip the mid-event service.

Owen is correct that a mid-event service visit is not typical for a 6-hour wedding with two units. However, the decision depends on the actual holding tank capacity of the units rented. A standard unit typically holds 50 to 70 gallons, and an ADA-compliant unit often has a similar or larger tank. For 100 guests over six hours with food and alcohol, the combined capacity should be sufficient without service. The rental company may suggest it as a precaution for high-use scenarios, but with good truck access already confirmed, a post-event service is standard. The main factor is whether the expected usage exceeds tank capacity, which is unlikely here.