Contaminated Water Diving: Classification, Suits and Decon Protocols
By Ray Whitfield, ADCI-certified commercial dive supervisor. Reviewed by Dana Whitcombe, technical reviewer.
Commercial Diving Contractors Alabama | Commercial Diving Contractors Alaska One early morning in a wastewater plant in Gary, Indiana, I climbed down a steel ladder into a primary clarifier. The water smelled like rotten eggs and looked like chocolate milk. My tender passed me the camera and said, 'You got twenty minutes before the pH starts eating your suit.' That dive taught me more than any class about contaminated water diving. The sludge wasn't just ugly. It was alive with bacteria, hydrogen sulfide, and a hundred other things you don't want in your bloodstream. Most people think a dry suit makes you invincible. It doesn't. It's just the first layer of a compliance process that starts before you touch the water and ends at the laundry. In this post I'm going to walk you through the way I've handled contaminated water dives for 28 years: how we classify the hazard, which suits actually keep the water out, and the decon protocols that keep us alive and compliant. No theory, just what happens at the job site.
Classifying the water: not all contamination is the same
Classifying contaminated water is the first step, and it's not as simple as 'if it smells bad, it's bad.' I've worked in industrial cooling water that was technically clean but held elevated levels of chromium, and I've worked in municipal sewer lines with coliform counts off the chart. The classification depends on the client's analysis, but as divers we rely on a few quick indicators: pH, conductivity, oxygen reduction potential, total dissolved solids, and the smell. Call it a WAG (wild ass guess) if you want, but it's informed by years of experience and a leakproof suit. Commercial dive standards and OSHA's HAZWOPER regulation (1910.120) talk about hazard assessments, but in reality you get a two-page report and a verbal 'be careful.' So we classify into three tiers: A for hazardous chemical/biological requiring gas-tight exposure suit, B for moderate contamination requiring a vulcanized dry suit with nitrile gloves and decon, and C for stormwater or muddy water that's only risky if it gets in your mouth. Depends on the plant. The lowest tier doesn't mean you skip decon. It means the decon is faster.
Suits that keep it out (and what goes underneath)
For heavy contamination, I wear a Trellchem chemical diver's suit over a standard dry suit. That's a heavy vulcanized rubber outfit with a gas-tight zipper and a steel emergency whistle. If you're diving in solvents or hydrogen sulfide, that's the only way to stay out of trouble. For most municipal and industrial jobs, a good dry suit with latex or neoprene seals is enough. I've used Viking suits for decades and they hold up well as long as they're cared for properly. The trick is what you wear underneath. In a refinery, the risk of flash fire is real. So my underlayer is a flame-resistant base layer that meets NFPA 2112. That layer has its own certification, and here's the thing nobody wants to say out loud: you cannot maintain that certification by washing it in a home machine. Once you wash it in a domestic washer, you've voided the FR properties. Same goes for the dry suit's seam integrity. That's why we send all our dive suits and FR underlayers to a commercial laundry that has TRSA Hygienically Clean certification or HLAC accreditation. They use validated wash cycles and drying temperatures, and they test the gear afterward. It costs more, but it's the only way to stay on the right side of NFPA 2112 and 70E.
The decon corridor: from the water to the wash rack
When I climb out of a contaminated dive, I don't just stand around while someone sprays a garden hose. We set up a three-bucket decon corridor: Bucket one is a gross rinse with clean water to knock off the heavy debris. Bucket two is a chemical wash. For raw sewage, I'm talking sodium hypochlorite diluted to about 1000 ppm, which is what OSHA 1910.1030 suggests for bloodborne pathogens. For hydrocarbons, we use a citrus degreaser. For acids, we use a weak baking soda solution. Bucket three is a final fresh-water rinse. Each bucket is lined and disposed of as hazardous waste. Nothing goes down the drain. The tender handles me like a HAZMAT team. He doesn't touch me until I've gone through the whole line, and then I take off my suit inside out. The suit gets inspected over an inflatable probe to check for pinprick holes. Then it goes into a contaminated-water bag and straight to the laundry. That laundry is the critical part. A cheap contract will tell you they can 'just wash it' and send it back. But if they're not following a validated process that meets TRSA Hygienically Clean standards, the suit comes back smelling clean but with unknown residue. You can't see microbes or flash point suppressants. That's the trap.
The laundry contract and the certification maze
I've seen dive operations cut corners on laundry because it's not the glamorous part. They'll have the diver take the suit home and wash it in the tub. That's a disaster. Not only does it void the suit's certification, it puts the diver's family at risk. So we have a contract with an industrial laundry that handles all our contaminated gear. The pricing model is simple: you pay per pound, per piece, or per employee per week. We pay per suit per week, and it runs about $4-15 per employee per week for regular uniforms, but for dive suits it's more like $50 per suit due to the size and the validation testing. The key is the contract must specify what you're getting: validated washing, microbiological testing, and a paper trail. If they won't put that in writing, walk away. A compliant decon protocol isn't just about the stuff you do at the job site. It's about the whole lifecycle of the gear. That's why I insist on a facility that can provide TRSA Hygienically Clean certification or HLAC accreditation. Those aren't just decorations. They mean the laundry audits its own process every time. Same goes for the FR underlayers: they have to meet NFPA 2112 and 70E for arc flash in certain settings. Home laundering will destroy the FR properties, and if a dive operation tries to save money that way, they're gambling with people's lives.
Frequently Asked Questions
What counts as contaminated water in commercial diving? It depends. The client samples the water, but I've seen jobs with almost no paperwork. When in doubt, treat it as contaminated. Municipal wastewater with high coliform, industrial process water with acids or solvents, or stormwater runoff from chemical plants all count. Can I wash my own dry suit after a contaminated dive? No. Home laundering doesn't meet any certified process and will void your suit's warranty and certification. Same is true for FR undergarments. You need a commercial laundry with TRSA Hygienically Clean or HLAC accreditation that can validate the wash cycle. What's the decon setup at a typical contaminated water dive site? Three buckets (gross rinse, chemical wash, fresh rinse) plus a line liner and a catch basin for the water. The tender uses PPE and the diver goes through the line before removing the suit. The suit is then inspected and bagged for industrial laundering. Do I need a special laundry certification for FR dive suits? If the dive suit includes an FR underlayer, that layer must be laundered in a facility that maintains the FR characteristics per NFPA 2112. Get the laundry to document its process and validation.