How Divers Keep Potable Water Gear Actually Clean
By Marisol Vega, Municipal water operations manager. Reviewed by Dana Whitcombe, technical reviewer.
Potable Water Tank Inspection & Cleaning | Wastewater & Sewer Diving On a 95-degree Tuesday in July 2019, I stood on a gravel apron next to the Clearwater Reservoir in Boise and watched a dive team break down their gear after a six-hour inspection shift. The air temperature was 38 degrees. The tank temperature was 55. The dive supervisor was down on one knee, wiping a scuba regulator with a red cloth. He didn't look up. 'You want to know the only thing between these lungs and 130,000 people?' He nodded at the cloth. 'This right here.' I manage 40 finished-water storage tanks. Every one of them is a closed system of concrete and steel that holds water meant for people to drink. That water is tested for chlorine residual, bacteria, and turbidity. But the divers who go inside carry their own little ecosystem—wetsuits, masks, hoses, weights—into a space that is not designed to be scrubbed. Over the years, I've learned that a diver's gear is the biggest controllable risk. This is the process we now mandate for every contractor that works in our system.
The Landside Wash: Soap Before Bleach
Dirty gear goes straight from the water into a 50-gallon wash tank filled with fresh potable water and a drop of dish soap. No detergent with fragrance, no enzyme cleaner. We use Dawn, because it's a degreaser and it leaves zero residue. Every piece—drysuit, undergarment, gloves, hoods, booties—gets scrubbed with a soft brush for at least two minutes. Wash the outside, then turn the suit inside out and wash the inside. That first rinse removes organic matter. Chlorine can’t kill what it can’t see, so this step is not skippable.
The Disinfectant Soak: Twenty Minutes Still
After the wash, gear goes into a second tank filled with a 200 ppm chlorine solution. The solution is made fresh on site, right before the soak. We submerge everything except regs and gauges—those have their own protocol. The soak lasts 20 minutes, not 25, not 15. The timer starts after the last piece is under the water. Over the years I've seen divers pull gear early because they're hot or bored. That's how contamination gets through. The chlorine solution is then tested with a pool test strip before you put the gear in. If the free chlorine reads between 150 and 250 ppm, you're in the zone. If not, dump it and mix again.
Hard Parts: Regulators, Gauges, and Mask Lenses
Regulators are the snake in this garden. They're full of small orifices and soft rubber parts. Submerging them in chlorine can corrode the metal seats and degrade the butyl rubber. So we don't. Instead, the second stage gets wiped down with a 70% isopropyl alcohol solution, and the first stage is flossed with a cotton swab dipped in alcohol. The mask gets a 2-minute soak in a mild hydrogen peroxide solution, then a rinse. The lens is cleaned with a microfiber cloth—no gritty polish. The concern isn't just keeping the gear clean; it's keeping it from breaking underwater. A $200 rubber part is not worth a trip to the hospital.
The Upstream Fight: Clean Gear, Clean Crew
Here's the part that surprises people: the gear is never perfectly clean. You can't sterilize a wetsuit. What we can do is keep it from getting dirty in the first place. Divers suit up through a 'clean zone'—a plastic sheet laid out on the tank apron. They don't walk on the ground in their booties. They wear nitrile gloves when handling gear after decon. The truck they carry the gear in is dedicated to potable water jobs. No street clothes inside. We also keep a set of gear specifically for potable water work; it never goes on a sewage or sea dive. That’s the only way to guarantee the chlorine and the tub wash are playing in your favor.
Verification: Check It, Then Log It
The last step is proof. After the decon, the dive supervisor takes a second free chlorine reading from the rinse tank to confirm the gear was, in fact, wetted by a disinfectant. He also swabs the face seal of the mask and the interior of the drysuit collar with a sterile cotton swab, which goes into a vial and off to a lab. We get a clean result about 40 times a year. Every decon gets logged in a binder: date, tank ID, diver names, concentrations, contact times. That binder is what a state inspector asks for first. It’s also what tells me a contractor actually follows the standard when I'm not watching.
Frequently Asked Questions
What happens if a diver pulls the gear out early? If the soak is cut short, the chlorine contact time isn't enough to kill the organisms that survive the wash. We've seen it happen once. That diver's gear was pulled from service, and the next job was canceled while we waited for a lab culture. The 20 minutes are not negotiable. Can you reuse the chlorine solution for the next dive? No. The solution gets consumed by organic matter and loses strength. We mix a fresh batch every time. A $2 bottle of bleach is not worth a potential contamination event. Is there an alternative to bleach for gear with membrane-sensitive materials? For drysuit valves or electronics, we use a hydrogen peroxide-based disinfectant at the manufacturer's recommended concentration. It breaks down into water and oxygen, so there's no corrosive residue. But the process is the same: wash, soak, rinse, test, log.