What is drain cleaner?

Drain cleaner was developed to unblock large, commercial waste water channels as well as individual drains within households. It is a chemical product, but the same terminology may be used to describe more mechanical methods for the same purpose, like plungers or drain augers. On occasion, the same term can also be used to describe the individual who undertakes in the unblocking of the drain.

To unblock a single drain, more commonly found in individual household systems like toilets and sinks, chemical drain cleaners are often used. If this method is successful, it can remove malleable materials, like oil and hair, which gathers near the basin of the device. If multiple drains are blocked then this is when electrical methods, like electric and battery powered cleaners, may be required. These methods can be utilised to remove blockages from entire lengths of pipe systems (from the unit’s basin to drains for the entire building and, even further, to the waste water mains.)

Every variety of drain cleaner has positives and negatives when used for every variety of situations. Different safety practices have to be considered and adhered to depending on the type of cleaner that is being used, as described below.

Chemical drain cleaner

Chemical drain cleaners can be more accessible for everyday use as they can often be found in hardware stores and can be purchased as solids or liquids. However, more acidic versions of chemical cleaners are still intended to be primarily used by qualified plumbers. The drain cleaners that can be purchased as a solid are often more alkaline than the more acidic counterparts, which are often purchased as a liquid.


Drain cleaners were developed alongside the drainage systems that became more widespread and common within the 20th century. Due to this, the history of cleaners in America is not well documented until the early 20th century when more American homes did begin to feature these systems. Before this, unwanted waste and water was often collected in basins after it had been used and was then disposed of. Lead was originally used to develop piping systems, but lead was discovered to be poisonous, after World War I, and so the systems were refurbished with galvanised iron.

Galvanised iron is actually steel encased in zinc, to protect it, but this was later adapted when it was realised that zinc can be affected and may corrode when exposed to the elements. The zinc corroding occurred down to the base material and so rust was formed. This then led to the drains becoming blocked due to a build-up of deposits which inspired the creation of drain cleaners.

Due to the corrosion that occurred on iron pipes, copper and plastics (PVC) were used to replace the original pipes by the 1960s. These new pipes did not contain zinc and so would not decay or expose the base metal. Materials like hair and oils still proved to be a problem as they still blocked the newer pipes. This was a catalyst for the creation of chemical drain cleaners which could eliminate these materials.

Chemical, alkaline drain cleaners predominantly contain sodium hydroxide (lye), which allows for it to dissolve heavier oils and hair. Potassium hydroxide is also used as a secondary ingredient for alkaline cleaners and these can be purchased as either a liquid or a solid.

Solid variants of the alkaline drain cleaner contain a caustic material (usually potassium hydroxide or sodium hydroxide), additives and aluminium particles. These additives usually contain wetting agents, like alkyl aryl sultanates, but the precise elements included in commercial drain cleaners are unknown as the combinations are different and specific to particular brands.

The aluminium particles, that are present in solid caustic drain cleaners, is an aluminium oxide which disintegrates and re-oxidises and produces gas (hydrogen.) The hydrogen released is an exothermic reaction and residual heat is also produced during this reaction. This heat then helps to break down the oils and hairs that may be blocking the drain. This reaction can be seen below.

Breakdown of aluminium oxide: AI203 + 2NaOH + 3H2O → 2Na[AI(OH)4]

Oxidation of aluminium metal: 2Al + 2NaOH + 6H2O → 2Na[Al(OH)4] + 3H2

The actual removal of the substance blocking the drain occurs when the substance reacts with the hydroxide ions (-OH) which are created by the drain cleaner. These substances blocking the drain are often natural ones like hair and oils and so are broken down via a saponification reaction of triglyceride and a base. Lye dissolves in the water and hydroxide ions are produced. These then attach the carbonyl carbons of the fat and this begins the hydrophobic tails of the triglyceride (e.g glyceryl trifoliate) to separate glycerol and a fatty, acidic salt.

Drain cleaners that can eradicate hair and oils (alkaline cleaners), do so via alkaline hydrolysis of amide and ester functionalities, as shown below.

RCONH2 (amide or protein) + OH− → NH3 + RCOO−
RCO2R’ (ester or fats) + OH− → R’OH + RCOO−

Due to solid lye being hygroscopic, it is imperative that the drain cleaner is placed directly next to the substance blocking the drain. This is to ensure that the lye doesn’t absorb the water going through the pipes, expand and then increase the size of the blockage, therefore making the problem worse.

Liquid alternatives of drain cleaner often include sodium hypochlorite (more commonly known as bleach) and lye (sodium hydroxide or potassium hydroxide) in concentrations of upwards of 50%. Alternative corroding solutions may initially come in separate parts which are mixed as they are poured into the drain. Within the drain, the two solutions mix together, form a gas and surfactants confine the gas by solidifying it as a thick foam. This foam is used to coat the interior of the pipe and the materials forming the blockage are then displaced. Liquid alkaline drain cleaners are heavier than water, as they are a base which is then dissolved in water, and so the formular can descend to the origin of the blockage.

Drain cleaners that contain high concentrations of sulphuric acid are known as acidic drain cleaners. These can disintegrate blockages formed by substances like cellulose and proteins like hair. They can also remove fats via hydrolysis.

Companies that produce acidic drain cleaners do list some potential hazards that may occur from their use. Some of these hazards include: an aggressive reaction with water, the creation of a combustible hydrogen gas upon interaction with the majority of metals, immediate or long-lasting health hazards if inhaled or ingested, and can cause serious burns to the flesh. If this substance comes into contact with eyes, it can potentially result in permanent blindness and can corrode any human tissue. The substance can also be fatal if it is swallowed. The reaction caused by these drain cleaners is so drastic that the drain cleaner must be added into the drain very slowly to minimise any potential hazards.

High concentrations of acidic drain cleaners hydrolyse fats and proteins (like hair) via acid hydrolysis. This is a similar process to the one caused by alkaline cleaners, but the reaction with acidic cleaners can be seen below.

RCONH2(amide or proteins) + H3O+ → NH4+ + RCOOH
RCO2R'(ester or fats) + H2O + H2SO4 → RCO2H + R’OH

High concentrations of sulphuric acid dehydrate materials that contain carbohydrates (for example, tissue paper which is made from cellulose:)

(C6H10O5)n + H2SO4 → 6n C + 5n H2O

Danger and usage considerations

Chemical drain cleaners tend to be readily available and easily accessible as they are often available at everyday retailers. Another advantage of them is that they are also fairly easy to use when removing everyday blockages, like hair and oils, that are near to the opening of the drain.

On the other hand, chemical drain cleaners can be less effective when a blockage if further down the pipe and not near the opening of the drain (for example, in a toilet.) They are also unable to dislodge the majority of solid blockages and do come with the safety precautions listed below.

A reaction can occur on the surface of many pipes between sulphuric acid and aluminium oxide.

Chemical drain cleaner is a dangerous substance as it can damage household items made from wood, aluminium or fibreglass and can cause significant damage to skin, lungs and eyes. Due to this chemical drain, cleaners should only be used following the guidance provided upon purchase from the manufacturer and using it any other way may result in serious injury. Corrosive and acidic drain cleaners are considered some of the most dangerous products that are on sale to the general population. Chemical drain cleaners can potentially also cause explosions and severe reactions when they come into contact with other chemicals that might have been applied previously. This can cause serious injury to anyone nearby when this happens. For example, a young boy was left scarred for life when an acidic drain cleaner dripped through the ceiling of his bedroom while he was sleeping.

Powerful alkali drain cleaners are just as likely to cause damaging and rapid burns as their acidic counterpart. There have been several cases of these substances causing damaging reactions. For example, a woman was attacked with concentrated lye and a young girl was scarred for life from an everyday lye drain cleaner. Another disadvantage of these products is that, as they are poured into the drain, they contribute to waste and pollution in the water supply. Heat being produced by the reactions caused by the drain cleaners can also lead to pipes bursting or can damage and soften PVC pipes (which are made from plastic.) Commercial drain cleaners, that are chemical based, may corrode pipes or cause damage or erosion to waste water lines.

On occasion, customers may unintentionally mix two varieties of drain cleaner, which can have disastrous consequences. For instance, the mixing of a basic and an acidic drain cleaner can be seen below.

Sulphuric acid + sodium hydroxide sodium sulphate (a salt) + water
H2SO4 + 2 NaOH → Na2SO4 + 2H2O

This reaction may seem as though it would neutralise the acid and base and so be safe, but this reaction can actually lead to pipes violently combusting as the reaction is exothermic. Below is another example of two variants being mixed, this time with bleach and an acidic drain cleaner.

Hydrochloric acid + bleach → water + table salt + chlorine gas

2HCl + NaClO → H2O + NaCl + Cl2

This reaction creates chlorine gas which is deadly and toxic to human lungs.

Handheld drain auger

Handheld drain augers are usually created to clear portions of a drain from the drain opening to about 8 m (25ft) into the drain. The cord of the drain auger is forced into a drain by a drum rotated by the machinist and anchors the cord.

The majority of handheld augers are narrow enough to fit through standard sink traps, but some creators do suggest not using these on toilets as they can mark ceramic fittings. To resolve this issue, a special closet auger (from the term water closet or WC) will be more effective for devices like toilets.

Drain rods are comparable to handheld augers, but these are better suited to pipes that are lengthy and unbending.

Some benefits of using handheld drain augers over other products include that they are readily available from everyday hardware shops, and they include a relatively low initial cost.

However, one of the disadvantages of handheld drain augers is that they are usually limited to only be able to reach 8 metres into the drain and, as previously mentioned, the twisting cable can mark ceramic surfaces. They can also only be used effectively on thin pipes (40-50 mm) and so cannot be used on main waste water pipes which have a diameter of 110 mm.

Protective gloves and goggles (or some other form of eye protection) must be worn when using handheld drain augers and good hygiene must be practised after being exposed to substances from the drains.

Air burst drain cleaner

Air burst drain cleaners use pressured gas, usually carbon dioxide or air, to breakdown the membrane of the blockage. Accelerated gas generates a force on still water and this breaks down the blockage that has formed close to the opening of the drain.

This method for unblocking drains is particularly useful as it allows for slow-moving or blocked drains to be cleared effectively and quickly whereas chemical drain cleaners can work more slowly. Air burst cleaners can also dislodge blockages that are close to the opening of the drain more effectively than a plunger and do not cause marks on ceramics, unlike the handheld drain auger.

In contrast, air burst cleaners do have a restricted range, especially in pipes that do not hold any standing water. They are also not particularly effective when used on main sewer drains or at eliminating blockages that are too far into the drain.

Goggles, or other apparatus to protect your eyes, must be worn whilst using an air burst drain cleaner. Gas canisters are also used with air burst cleaners and so care must be taken when using and handling these canisters.

Home remedy drain cleaners

Various home remedies exist for cleaning drains including pouring boiling water down the drain opening to remove blockages of soap or hair. Another method is pouring baking soda and vinegar into the drain to cause a reaction.

The method using baking soda and vinegar is not dangerous but isn’t particularly effective although this is often recommended as an at home drain cleaning method. As baking soda is a weak base and vinegar is a weak acid, the logic behind the reaction is sound as the baking soda can saponify oils and the vinegar can neutralise, but the weak nature of both items means that it is mostly ineffective. A stronger product, like lye, is needed to convert oils into soap. Using stronger products together, however, like lye (sodium hydroxide) and hydrochloric acid, is a worse combination. These two items do not mix well together, and they neutralise each other which makes them unsuccessful. The reaction would cause a build-up of heat and this can cause damage to the pipes. Another damaging combination is acids being combined with bleach as this will produce hazardous chlorine gas.

Home remedy drain cleaners can be beneficial as they are readily available and safe for the environment. However, they do tend to be less effective than other drain cleaners like chemical cleaners.

It is suggested that boiling water should not be used to clear drains as it is 100C and this surpasses the Vicat hardness (thermal deformation temperature) of PVS drain line (65C.) This means that it can melt the ring, which the toilet is mounted on, as it is made from wax.

Handling different chemical items needs to be considered carefully when using home remedy drain cleaners and great care needs to be taken when using these products at home.

Hydro-mechanical drain cleaners

Hydro-mechanical drain cleaners push pressurised water through the drain so that the blockage is broken up and flushed down the drain.

The majority of city building codes state that pipes must increase in diameter as it moves closer to the main sewage system. For example, an average kitchen sink has a pipe that has roughly a 1 ½ inch diameter which is then connected to a 4-inch pipe which is eventually connected to the city sewage system. This system means that, unless roots from trees or other waste disrupts the underground pipes, most household drains become blocked in the thinnest part of the pipe (usually in the drain trap or the pop-up.) Blockages in these parts of the pipes can be reached with ease by a hydro-mechanical drain cleaner’s hose.

A benefit of hydro-mechanical drain cleaners is that they’re very environmentally friendly as most of them utilise tap water. They are also unlikely to damage plumbing joints and are able to remove blockages, like sand, that are harder to permanently remove with other drain cleaners like conventional augers. Hydro-mechanical cleaners, unlike air-burst cleaners, do not use pressure in the pipes and so are much safer to use. Some variations of hydro-mechanical drain cleaners have functions for both hot and cold water which mean that they have additional cleaning power for other substances like fats or proteins which can be cleared by melting them.

On the other hand, hydro-mechanical drain cleaners do require a nearby water source for them to be able to operate. They do also have a limited range that they are successfully able to function within the drain and so are not suitable for every drain blockage.

The high-pressure water needed for a hydro-mechanical drain cleaner does come with some safety risks as it can cause injury if it comes into contact with skin or more fragile parts of the body (e.g eyes.)

Electric drain cleaner

Electric drain cleaners (also known as plumber’s snakes) use mechanical energy from an electric engine to force a cable or spring into a pipe in a clockwise direction. These are readily available with cables being available from up to 40 metres meaning that they can reach up to 80 metres within the drain.

Electric drain cleaners are very effective at unblocking long sections of the pipe, and they are able to extract solid items from the drain (like roots or jewellery.) They are also easily accessible and can be purchased from most hardware shops or stores where machinery like this can be rented. Variants of electric drain cleaners that use a spring can effortlessly fit through 90 bends in the pipes without harming the pipes and whilst still effectively clearing the blockage.

Unfortunately, electric drain cleaners do have a much higher relative cost and are much heavier than most other drain cleaners. They also require a great deal of physical exertion to operate, especially if the cable is hard to control due to its length.

Protective gloves and goggles, or other eye protection, must be worn whilst electric drain cleaners are being operated. Care also must be taken when operating the machinery as it does rotate and the cable must carefully be controlled so that it doesn’t become overstressed. Correctly grounded electrical sources must also be used when operating this sort of machinery as electrical faults or weak fixtures can result in injury.

Water jetters

Jetting a sewer involves pushing pressurised water being pushed into the drain so that any waste blocking the channel for the water can be removed. This is often more effective than using plumber’s snakes or drain rods as the power of the pressurised water is far greater than any pressure that can be achieved through manual work. Water jetters are also so effective due to water’s ability to easily manoeuvre around corners within the pipe system and reach spots that other manual cleaners cannot reach.

A water jetter consists of a highly pressurised water supply (usually from a pressure washer or a displacement pump), a pliable high-pressure line (which can be hundreds of metres long,) a mini-reel and a nozzle which uses hydraulic power to manoeuvre the line into drains, clean the interior of the pipe and push out any remaining waste. The high-pressure line is called a jetter hose and attaches the engine to the mini-reel and the mini- reel is a hose reel which can be extended and placed away from the engine. Water jetters can be attached to vans, trailers or trolleys and the can range in how powerful they are (from 1,000 psi to 5,000 psi.)

A variety of water jetter nozzles are available for different specific purposes. A bullet-type nozzle is streamlined and is used to create a hole so that the larger root cutting nozzle can be used later. A root-cutting nozzle spins and sprays a water stream horizontally along the pipe. Pressurised water jetters with a root-cutting nozzle can clear through a drain that is overrun with tree roots. The device’s rear-facing jet of water can also clean the interior of the pipe and fully clear the waste water line.

A water jetter has been identified as a technological development of the original plumber’s snake or electric drain clearing methods.

Water jetters are also available as portable devices, as well as pressure washer water jetter attachments, and these are predominantly used by homeowners or service workers to destroy soft blockages within their drain systems and to stop the reoccurrence of similar blockages. Pressure washer water jetter attachments are usually cheaper and lighter than drain cleaners that are electrical and can reach the same distance. They are also less likely to scratch plumbing attachments and are so are a good option for homeowners.

Water jetters that can be mounted onto vans and trailers are usually used by larger organisations as they require the higher hydraulic power that can be provided by strong displacement pumps. These strong pumps mean that more substantial, solid blockages and tree roots can be removed by the water jetter.

Water jetters are a popular method for drain cleaning as they can reach a large length of pipe fairly simply and easily. As they can both clear the blockage of the drain and clean the interior of the drain, they also reduce the requirement of further drain cleaning to take place.

Many portable water jetters and pressure washer water jetter attachments are unable to remove solid blockages and large tree roots and this is one of their main disadvantages. Trailer-mounted water jetters would be more suited to such tasks, but they are extremely heavy and are more expensive than their counterpart. They do also require a large amount of training so that they can be used according to safety guidelines and so are not accessible for everyone.

To use water jetters, goggles or some form of eye protection must be worn as well as safety gloves. This is to ensure that the user does not come into contact with any of the fluids from the drain and that the nozzle only works inside the waste water pipe. To use large water jetters, a large amount of specialist training is also required so that safety guidelines are adhered to so that injuries can be avoided and minimised.