 a drain cleaner is a chemical based consumer product that unblocks sewer pipes or helps to prevent the occurrence of clogged drains. the term may also refer to the individual who uses performs the activity with chemical drain cleaners or devices known as plumber's snake. drain cleaners can be classified in two categories: chemical, or device. *if a single sink, toilet, or tub or shower drain is clogged the first choice is normally a drain cleaner that can remove soft obstructions such as hair and grease clogs that can accumulate close to interior drain openings. chemical drain cleaners, plungers, handheld drain augers, air burst drain cleaners, and home remedy drain cleaners are intended for this purpose. *if more than one plumbing fixture is clogged the first choice is normally a drain cleaner that can remove soft or hard obstructions along the entire length of the drain, from the drain opening through the main sewer drain to the lateral piping outside the building. electric drain cleaners and sewer jetters are intended for this purpose. each type of drain cleaner has advantages, disadvantages, and safety considerations as described below. ==chemical drain cleaners== chemical drain cleaners can be in solid or liquid form that are readily available through hardware stores, though some (primarily acidic ones) are intended for use by licensed plumbers. alkaline drain cleaners are available in either solid or liquid state while the acidic ones are usually in liquid form. thumb|200px|solid formulation of an alkaline drain cleaner. ===alkaline drain openers===  alkaline drain openers primarily contain sodium hydroxide and some may contain potassium hydroxide. they may appear in liquid or solid form. liquid formulations of corrosive alkaline drain cleaners can contain sodium hypochlorite (bleach) and lye (sodium hydroxide or potassium hydroxide) in concentrations up to 50 percent. other corrosive mixtures come as two-part cleaners that are mixed as they are poured in the drain opening. inside the drain the two solutions react to release a gas, and surfactants trap the gas as dense foam. the intent of this foaming action is to coat the inside of the drain pipe to dislodge more of the substances that form the clog. solid formulations of corrosive alkaline drain cleaners in the form of 
Plumbing