Picture yourself and your family on vacation in Hawaii (or if you live in Hawaii and a staycation doesn't sound appealing to you, perhaps you're in Mexico). You've checked into your five star resort and your kids absolutely CANNOT wait to go to the pool and ride that awesome water slide that they've been so patiently waiting for. The family is all suited up, sunblock has been applied, tennis shoes have been abandoned for flip flops, and each person has their towel under their arm. IT'S GO TIME.
As your family strolls (or runs) down to the pool area, the group is dismayed to see caution tape across the gate and a sign stating, "OUT OF ORDER UNTIL FURTHER NOTICE". Confused, you ask the nearby maintenance worker what's going on and when they expect the pool to re-open. He looks at you out of the corner of his eye and says, "Take a look at that water, dude. Your guess is as good as mine."
Peering through the fence at the water in the pool, you now notice that what you previously thought was trees and surrounding buildings reflecting off the surface of the water is really what appears to be sewage floating in the water...
Well... that's exactly what it is.
You see, when the pool was constructed, the plumber didn't provide an air gap between the pool drains and the sanitary drainage system. As a result, sewage was able to freely make it's way into the pool when the City's sewer backed up, creating an unsanitary and unsafe condition. Not only does this vile scenario affect the patrons of the resort, this will also cost A LOT of money to fix.
BUT, the plumber should not bear all of the heat of this mess. After all, the engineer designed it without an air gap, the code violation wasn't caught at the time of the City's plan review, and the plumbing inspector didn't catch it either.
That's right, this unfortunate incident is a direct result of a code violation. Chapter 8 of, both, the International Plumbing Code (ICC) and the Uniform Plumbing Code (IAPMO/ANSI) contains requirements for indirect drainage which are intended to protect the health and well-being of individuals like yourself and your disappointed little family (But don't worry. You're in a tropical location, so there's always the beach!).
Take note that swimming pools aren't the only condition where indirect drainage is required. Chapter 8 of the IPC also requires this for commercial food-handling fixtures and equipment, commercial dishwashers, food storage areas, health care equipment (sterilizers), equipment that discharges potable and non-potable clear water waste (relief valve piping, condensate drainage, etc.), etc.
Additional requirements for residential dishwashing machines can be found in IRC section P2717.
So what is indirect drainage? And what is the difference between an air gap and an air break?
Put simply, indirect drainage is a means of preventing backflow of contaminants, such as bacteria and raw sewage, from the sanitary waste system (building drain and sewer) back into fixtures, equipment, appliances, and even into the domestic water system. You'll need to pay close attention as you go through Chapter 8 and make the careful distinction between whether an air gap or an air break is required. Take note that an air gap provides a higher level of protection from backflow than that of an air break.
Air gaps - A fixture's discharge piping must terminate a minimum of 2x the diameter of the discharge piping above the flood level rim of the waste receptor (such as a standpipe, hub drain, or floor sink). An air gap should provide open air (free atmosphere) between the end of the discharge pipe and the waste receptor below.
Air breaks - A fixture's discharge piping is permitted to discharge below the flood level rim of the waste receptor, but must terminate above the trap seal.
In summary, indirect drain connection requirements are important to grasp, employ, and enforce. Your health (and the swimming pool) depend on it.
Written by Brendan Pendley, owner of Check-It Code Consulting, LLC
All code references are taken from the 2018 I-codes unless otherwise noted.
