Why does our porta potty smell fine at first, then get bad quickly?

Heat speeds it up, but with 15 guys on one unit and one service a week, the bigger issue is usually that the tank is filling up well before the truck comes back. Once waste climbs past the blue water, the deodorizer gets diluted to the point where it can't keep up, and hot weather gets you there faster.

We hit the same wall on a summer rehab with a crew about your size. One box was legal under OSHA 1926.51 since we were under 20 workers, but legal and pleasant aren't the same thing.

Things worth asking your rental company:

• Are they pumping the holding tank all the way down and recharging it with fresh chemical every visit, or just topping it off?
• Can the driver note how full it is when he shows up? If it's near the top on service day, you need more capacity, not stronger chemical.
• What does a second service visit each week look like on the quote, versus adding a second unit?

We went to a midweek service and the day four smell pretty much stopped. Also look at the vent stack on the roof and make sure it isn't cracked or blocked, and remind the crew to keep the door shut. If the unit sits in full afternoon sun, ask them to move it into some shade on the next service.