Chemical Drain Cleaners: Types, Hazards and Safer Options

The main types of drain openers

The active ingredient on the label tells you what you're dealing with. Check it before you buy, and again before you pour.

MedlinePlus lists lye, potassium hydroxide, sulfuric acid and hydrochloric acid as the poisonous ingredients in drain openers. One gel clog remover's product page describes it as a thick bleach formula that pours through standing water. At the gentle end, the same maker's FAQ describes its enzyme product as using microorganisms to break down residue over time, to prevent clogs rather than open them. Its directions call for leaving it 6 to 8 hours, and the FAQ says it will not open a completely clogged toilet.

The hazards: burns, splashes and fumes

Drain openers are made to dissolve hair, soap scum and grease, and skin and eyes are no match for them. MedlinePlus explains that drain opener poisoning happens not only when someone swallows the product, but also when it splashes into the eyes during pouring or when someone breathes the fumes of foaming openers. It warns that eye exposure is very dangerous and that vision loss is common.

Acid openers add a heat hazard. NIOSH's pocket guide entry for sulfuric acid lists eye and skin burns among its effects and notes that it reacts violently with water, releasing heat. Follow the pouring directions on an acid product exactly.

The bleach-based gel's product page tells users to keep hands, face, children and pets away from the drain while it works, not to squeeze the bottle or splash the product, and to clean up spills at once. Professionals take the same products seriously. The K-400 drain-machine manual tells operators to wear rubber gloves, goggles, a face shield, protective clothing and a respirator when chemicals are suspected in a drain line.

Never mix products, and never chase one with another

New Jersey's health department puts it bluntly: never mix cleaning products, especially anything that contains bleach. Its hazard alert says bleach mixed with drain openers, ammonia or acid-based cleaners can release toxic gases, chloramine with ammonia and chlorine gas with acids. It also warns that different brands of drain cleaner can react dangerously with each other.

The CDC's chlorine fact sheet gives the same warning about household bleach and other cleaners. The bleach-based gel's product page says not to use or mix it with any other cleaner or chemical, because hazardous fumes or a violent reaction may result.

In practice, that means:

• If one product didn't clear the drain, don't pour a second one on top of it.
• Don't follow a bleach gel with an acid opener, or the other way around.
• Don't clean the sink with bleach or an ammonia cleaner while an opener is still sitting in the pipe.

If a mix happens anyway, the CDC's advice for a chlorine release from household cleaners is to open windows and doors and leave the area until the gas has cleared.

After you pour: no plunger, no snake, and tell the plumber

The bleach-based gel's product page says never to use a plunger during or after use, because product may still be in the drain if it didn't clear. If a garbage disposal drain doesn't clear, it says not to turn the disposal on, since the product may splash back, and to consult a plumber.

The same reasoning applies to a hand auger or to taking the sink trap apart: whatever you poured is still in the standing water. A spinning cable throws off liquid and debris, which is why the K-400 manual offers an optional guide hose to help contain it.

Tell anyone who works on the drain exactly what you used, and keep the bottle. The same manual tells operators to find out whether drain cleaning chemicals are present and, if so, to get the specific safety measures from the chemical's manufacturer. New Jersey's alert describes a plumber who poured an acid drain solvent into a drain that smelled of bleach. The mix released chlorine gas, and the plumber went to the emergency department with breathing problems.

Why they fail on main-line and root clogs, and what they do to pipes

Drain openers are sold for single fixtures. The FAQ cited above says its clog removers are for sinks, showers and tubs, not toilets, and explains that a toilet's built-in trap keeps the product from reaching the places where clogs build up.

A main-line clog is a different problem. When several fixtures back up at once, the blockage is usually far down a pipe they share, under the floor or out in the yard; our list of main sewer line clog signs explains how to tell. A product poured into one sink then sits in backed-up water above the blockage, which is the situation the label warns about when a drain doesn't clear.

Roots are another mismatch. The gel's page names hair, soap scum and grease as its targets and doesn't mention roots. Root problems call for cutting, jetting or repair, covered in our guide to tree roots in sewer lines.

What these products do to pipes is mostly a matter of manufacturers' claims, so read them as claims. The maker cited above says its products are safe for plastic and metal pipes when used as directed. Its FAQ also warns that sulfuric- and hydrochloric-acid cleaners can damage porcelain and metal when used incorrectly and should be a last resort, used only by a professional. NIOSH lists sulfuric acid as corrosive to metals. Drain chemicals are hard on professional equipment, too: the K-400 manual lists corrosion from exposure to drain chemicals among the kinds of damage that weaken a cleaning cable.

If someone is exposed

Call Poison Help at 1-800-222-1222, which connects you to your local poison center. Poison Help's first steps are:

1. Breathed in fumes: get to fresh air right away, then call.
2. On the skin: take off any clothing the product touched, rinse the skin with running water for 15 to 20 minutes, then call.
3. In the eyes: rinse with running water for 15 to 20 minutes, then call.

Keep the bottle handy, because MedlinePlus says the product name, ingredients and strength help the people advising you. MedlinePlus also says to get medical help right away, to call 911 or Poison Help after an exposure, and not to make the person vomit unless poison control or a health care provider says to. If someone is struggling to breathe or has collapsed, call 911. See a doctor if you feel ill after any exposure.

Bottom line: try these first

For one slow fixture, mechanical tools are the safer first step: a cup plunger for a sink or tub, a flange plunger for a toilet, pulling hair from a shower drain, cleaning the sink trap, or a hand auger. Our guide on how to unclog a drain yourself walks through each one. Enzyme products are for slow buildup and maintenance, not for a blocked drain.

To keep clogs from forming, see what not to flush or pour. If several fixtures are involved, or the same drain keeps clogging, skip the bottle and call a licensed plumber; our comparison of drain cleaning methods explains what they're likely to use.