How to Open a Drain That May Hold Chemical Opener

Why this matters

The customer who calls about a clogged sink has usually already tried something, and the something is often a bottle of caustic or acid drain opener that did not work. It is now sitting in the standing water and the trap, at a strength nobody can see, waiting for the first plunger stroke or slip-nut turn to put it in somebody's eye. Alkali burns to the eye keep penetrating after the splash, which is why a drain opener splash is an emergency room event, not a rinse-and-carry-on. The whole job is decided before the trap comes off: ask, read, test, dress, and add nothing.

What may be sitting in the trap

Three families of product end up in residential drains, and they behave differently enough that the first job is knowing which one you have.

• Caustic (alkaline) openers. Sodium hydroxide (lye) or potassium hydroxide, as a gel, liquid or crystals. Gels often add sodium hypochlorite (bleach). Some crystal products include aluminum flakes that react with lye to make heat and hydrogen gas, which is how they "boil" in the drain. A caustic trap reads pH 12 to 14 and feels slippery on a glove.
• Acid openers. Concentrated sulfuric acid is the professional-strength product sold to homeowners; hydrochloric (muriatic) acid turns up as toilet bowl cleaner poured into a sink. Concentrated sulfuric acid releases a great deal of heat when water meets it, enough to boil water at the contact point and throw it.
• Enzyme and bacterial products. Low hazard and slow. Treat them as unknown until a label says otherwise.

The dangerous case is two products. Acid poured onto a caustic gel makes heat, and if the gel carried bleach, chlorine gas. See related: Mixing Cleaners and the Gases They Make, which owns that chemistry.

Step 1: Ask at booking, in words the customer will answer honestly

People leave out the bottle because they are embarrassed it did not work, or they assume it no longer matters. Ask directly and make the answer cheap to give. The office asks once, the tech asks again at the door, because the answer changes: a second product often goes in between the call and the visit.

OFFICE:   Before we come out, did anybody pour
          anything down it? Drain opener, bleach,
          bowl cleaner, anything at all?
CUSTOMER: I tried some of the gel last night.
OFFICE:   That's normal, and it helps us. Can you
          keep the bottle out for the tech? And
          please don't pour anything else in.
CUSTOMER: My husband might have used the other one
          this morning.
OFFICE:   Okay. Leave that bottle out too, keep the
          sink off, and keep the kids away from it.

The note on the work order names the product type, the time, and "two products possible" when that is the answer. Skip this and the tech meets the trap blind, and the first sign of what is in it is the splash.

Step 2: Read the label before you look at the drain

Find the bottle and read the hazard statements and ingredients. You are looking for the signal word (DANGER on most), the active ingredient class (sodium or potassium hydroxide, sulfuric or hydrochloric acid, sodium hypochlorite), and the first-aid statement. Photograph the label for the job record. If the bottle is gone and the customer cannot say what it was, the working assumption is an unknown corrosive, possibly two, and every later step is done at that level.

The reason this comes before the drain is that your protection depends on it. Glove choice for concentrated sulfuric acid is not the same as for lye, and the bleach line on a label is what tells you a chlorine smell is possible. See related: How to Choose a Glove from the SDS.

Step 3: Take the fixture out of use and clear the area

Shut off and tag the fixture: a strip of tape across the faucet handle, the disposal switch, and the dishwasher, because a dishwasher pumping out into a sink full of caustic water raises the level and splashes it. Ask the customer to keep children and pets out of the room; that is ordinary duty of care toward a household, since OSHA's standards cover your employees, not the people who live there. Open a window or run the range hood if you can do it without leaning over the bowl.

Skip this and someone runs the tap while you are under the sink, the standing water rises over the overflow or the open trap, and you take a stream of it on the arms.

Step 4: Dress for a splash to the face, not for dirty water

The protection is chosen for the product named in step 2, and the default for an unknown corrosive is the full set:

• Indirect-vent chemical splash goggles plus a face shield over them. A face shield alone is not eye protection, and safety glasses let liquid run around the lens. 29 CFR 1910.133 requires eye and face protection where employees are exposed to liquid chemicals, and 29 CFR 1910.132(d) requires the hazard assessment that selects it, certified in writing, for general-industry work; construction work falls under 1926.102, which carries the eye and face duty but not the written certification.
• Chemical-resistant gloves with a long cuff. Neoprene or butyl covers both caustic and concentrated acid in most glove charts; nitrile handles sodium hydroxide well and is a poor choice against concentrated sulfuric acid. Under a sink, your hands are above your elbows, so fold the cuff back into a drip lip, or liquid runs inside it down to the wrist. See related: The Skin Route and What Gloves Actually Stop.
• Long sleeves and an apron or disposable coverall. Cotton holds caustic against the skin; a coated apron sheds it.
• Flushing water within reach. 29 CFR 1910.151(c) requires suitable facilities for quick drenching or flushing where eyes or body may be exposed to injurious corrosive materials, and 1926.50(g) carries the same requirement for construction. A squeeze bottle is a supplement that buys seconds, not a flushing station; ANSI/ISEA Z358.1, the consensus standard OSHA looks to for what "suitable" means, describes an eyewash delivering a continuous flow for 15 minutes. On a residential call the practical answer is a self-contained eyewash in the van plus a tap you have confirmed runs, and both get named before you start.

If it splashes: eyes go under flowing water immediately, lids held open, for at least 15 minutes, and anyone with a caustic or acid splash to the eye goes to emergency care; call 911 rather than driving them. Skin: remove contaminated clothing and flush for at least 15 minutes. Poison Control (1-800-222-1222 in the US) can advise while you flush, with the label you photographed.

Step 5: Test the standing water before you disturb it

Dip a pH strip in the standing water with a disposable stick or a dropper, never a finger, and read it against the chart. Note the smell (bleach or a sharp, swimming-pool chlorine odor), any bubbling, and whether the trap feels warm through your glove.

• pH 12 or higher: strong caustic is still present.
• pH 2 or lower: acid is present.
• Roughly 6 to 9: the product is spent or diluted, which lowers the risk, not removes it, because a trap can hold a stronger layer below the water you tested.
• Warm, bubbling, or a strong chlorine smell: a reaction is still running. Stop here. Back away from the fixture, ventilate the room, and let it finish; if the smell is strong or anyone is coughing or short of breath, everyone leaves the room and you call 911 or Poison Control from outside.

Skip this and your protection is a guess. A reading of 13 on a trap the customer swore was "just water" is common.

Step 6: Add nothing, plunge nothing

This is the step people break, because each tempting move looks like progress.

• No neutralizing in the fixture. Pouring vinegar onto caustic, or baking soda or a caustic opener onto acid, makes heat and gas inside a confined trap with your face above it.
• No second product, no hot water. Hot water on concentrated sulfuric acid spatters, and on a caustic gel it does nothing a mechanical tool will not do better.
• No plunger and no powered auger fed through the fixture opening. A plunger is a pump; its return stroke throws the bowl's contents up and out. A spinning cable in a bowl of caustic flings it.

Step 7: Drain the trap into a container, then clear it mechanically

Bail the standing water down with a small cup into a heavy plastic (HDPE) bucket, slowly, pouring low so it does not splash. Then set the bucket under the trap, loosen the slip nuts by hand with your face turned away and the face shield down, and let the trap drain before you pull it off. Feed the cable through the trap arm or a cleanout, not through the bowl, with a rag around the opening. Keep the bucket away from aluminum tools and fittings, which caustic attacks with hydrogen as the product.

Once the line runs, the bucket goes back down the cleared drain a little at a time with cold water behind it, where the product was designed to go; the van does not carry corrosive liquid away. Rinse the cable, trap and tools before they go on the truck, and rinse your gloves before you take them off.

Step 8: Reassemble, run it, and record what was in there

Replace washers that have swollen, which caustic does to rubber, run water, and check every joint with a dry paper towel. Leftover product is household hazardous waste; point the customer to the local collection program. The record gets the active ingredient, the label photo, the pH, any reaction, the PPE worn, and any splash and its response.

Worked example: a kitchen sink with a caustic gel and a maybe

The work order reads: kitchen double sink, left bowl not draining, customer used gel opener last night, "second product possible." At the door the customer produces one bottle; the ingredient list names sodium hydroxide and sodium hypochlorite, signal word DANGER. Asked about the second product, the husband says he thought about the bowl cleaner and did not use it. The tech asks to see it anyway: it is a hydrochloric acid cleaner, still sealed under the cap's foil.

The left bowl holds standing water about 3 inches deep. At roughly 16 by 14 inches, that is about 670 cubic inches, close to 3 gallons, which means a 5-gallon bucket takes it in one go. The tech tapes the faucet and the disposal switch and finds the dishwasher mid-cycle, which drains into this side; it gets paused and tagged. A window is opened.

Goggles, face shield, neoprene gloves with the cuffs folded into a lip, apron, and the van's eyewash on the counter with the tap confirmed running. The pH strip reads 12. There is a faint bleach smell over the bowl, no bubbling, and the trap is cool, so no reaction is running, but strong caustic is still present.

The tech bails the 3 gallons into the bucket, pouring low, and the trap gives up perhaps a pint more when the slip nuts loosen. The clog is grease about 2 feet into the trap arm; a hand cable through the arm clears it. The bucket goes back down slowly with cold water following, one swollen washer is replaced, and the joints stay dry.

The record notes: hydroxide and hypochlorite gel, pH 12, no reaction, full splash kit, no exposure. The customer hears that the gel could not reach a grease clog that far down and gets the county drop-off for the leftover bottle.

What changes the answer. Had the husband said he poured the bowl cleaner in this morning, step 5 would have looked different: a warm trap, a strong chlorine smell, maybe bubbling. That is the stop in step 5, not a reason to work faster. The room is ventilated, the fixture left alone, and the tech waits outside the kitchen until the smell clears and the trap is cool, then re-tests before doing anything else; anyone coughing means 911 from outside. The same stop applies to a bowl that reads pH 1 with heat coming off it, which is concentrated acid still reacting with the water.

References

• OSHA 29 CFR 1910.132, 1910.133 and 1910.151(c); 29 CFR 1926.102 and 1926.50(g) for construction work
• ANSI/ISEA Z358.1, Emergency Eyewash and Shower Equipment, in the edition current for your equipment
• America's Poison Centers, Poison Help line 1-800-222-1222
• See related: Mixing Cleaners and the Gases They Make
• See related: How to Choose a Glove from the SDS