What is a dry closet: the principle of operation and the specifics of using autonomous plumbing

Nikolay Fedorenko
Checked by a specialist: Nikolay Fedorenko
Author: Lydia Korzheva
Last update: November 2019

The lack of a central sewage system is not a reason for refusing comfort anywhere. Whether it is a summer cottage, a construction site or a picnic in a place remote from the benefits of civilization, a mobile, compact and hygienic dry closet will become an indispensable attribute.

And what is a dry closet, by what principle does it work, how to use it, you will find all these details in the article.

Existing types of dry closets

The classic dry closet is a sanitary construction based on the natural decomposition of waste. The process is accelerated through the use of biological, natural components. Present here and artificial drying, and ventilation which is implemented with the help of electrical appliances.

It is compact, do not contradict all sanitary standards. The main advantage is that you can use this plumbing device anywhere because you do not need to connect it to the sewer.

Dry closet and bad smell
The dry closet is convenient also that does not exude an unpleasant smell. Its elimination was originally laid down in the principle of operation of the device

For the processing of waste in dry closets, chemical solutions and natural mixtures are used, the basis of which are the following products:

  1. Peat. This component absorbs all the fluid and processes waste by mineralization.
  2. Compost. It works in a dry closet tank as well as in a compost pit.
  3. Sawdust. They are practically not used in their pure form. If they are used, then only paired with peat.
  4. Powder mixtures. These are loose fine-grained preparations that absorb liquid well and provoke the process of complete waste processing. They are produced specifically for dry closets.
  5. Microflora. It is a liquid containing bacteria that dispose of waste.
  6. Bioenzymes Liquids based on a mixture of enzyme proteins and bacteria that decompose organic waste.

Dry closets are different in design, but they have one thing in common - two containers. One of them is a toilet, and the second one collects waste and is recycled here. Knowing how to use your home dry closet, you can significantly improve the quality of accommodation both in a house outside the city and in a city apartment.

There are two large groups of these devices: mobile and stationary. The first is a design with small dimensions. There are no difficulties with it either during transportation or during installation. With such a device, you can go even to the country, at least for a picnic, even for a long car trip.

The second group - dry closets cabins. They are equipped with a removable container. When it is filled, it is replaced by another.

Toilet cabin
Toilet cabins made of high quality materials are quite comfortable. The main thing is to timely carry out maintenance and replenish consumables

Visually, all models are ordinary toilets, but the principle of functioning is different.

On this basis, they are divided into two types:

  • Composting. These include peat and liquid-free models. In the first case, the liquid is not diverted, but participates in the processing process. The second type includes all electric autonomous toilets in which the waste is processed into compost as a result of liquid removal from the mass, drying and pressing.
  • Liquid. They are chemical and biological. The means created on the basis of formaldehyde are poured into the storage tanks of the first, therefore the processing result cannot be used as compost. A substance containing bacteria and bioenzymes is poured into the tanks of biological models. What forms in the tank after they work goes to compost.

At choosing a dry closet focus on the appropriate method of processing, the possibility of disposal or accumulation of waste, the type of liquid or mixture, model and cost.

Peat Toilet Specifics

A dry closet of this species is also called peat or Finnish. If you choose a plumbing device according to the principle of work, such a dry closet is the simplest. It fully corresponds to the name “dry closet”, as only natural components are involved in waste processing.

The main disadvantage of the peat dry closet
As a disadvantage of the dry closet, a specific “aroma” of the filler can be noted. For this reason, it is better to place it in an isolated room or on the street.

With this method of disposal, liquid is not needed. Waste is adsorbed by peat.

Features of the device and installation

In some cases, the Finnish dry closet is supplemented with an exhaust pipe, it is led out into a special hole or in the window. It should occupy a vertical position, height - at least 2 m. If there is a cesspool or compost pit nearby, a hose for discharging liquid waste can be built into the lower part.

Lay the hose in a trench with a depth of not less than 1.5 m, which will insure against freezing of liquid in the winter. Such an improvement will reduce the consumption of filler, increase the intervals between the removal of content.

How to operate peat dry closet?

The composting toilet is based on the division of waste accumulated in the tank into separate components: solid, liquid and their further splitting. Outwardly, it resembles a classic toilet, but instead of water in the tank, peat or another adsorbent. After each use, fill the filler.

For peat to enter the dry closet capacity, a metering pen is included in the design. After two or three times its rotation, all the contents are covered with peat. This creates a favorable environment for the life of microorganisms that convert waste into useful compost.

Dusting waste in a dry closet
The waste powder tank, located in the usual place for the flushing tank, is not provided in all models. If you purchased a model without it, you will have to carry out the procedure yourself using a scoop. The container with peat or sawdust in this case is located separately

There are designs with an electric dispenser. Then a prerequisite is its connection to the mains. The required amount of peat per 10 l of waste is only 1 kg. To increase its moisture absorption capacity, peat is sometimes combined with sawdust.

The contents of the dry closet will turn into compost, which you can fertilize the garden garden in two years, and until that time it is kept in a compost pit.

You can read more about how to clean dry closets in this stuff.

The best models of peat dry closets

High quality aesthetics, versatility and mobility, comfort and aesthetics - this is how you can characterize most models of peat dry closets.

Among them:

  • Tandem Compact-M;
  • Tandem Compact Eco;
  • Compact Lux M;
  • Piteco 506;
  • Piteco 905;
  • Bioecology Ecolight Summer Resident;
  • Kekkila Eco Green.

These are mainly stationary structures. They are compact, made of different materials, have a different set of components.

# 1: Model “Tandem Compact-M”

This model is a stationary design with a storage tank of 60 liters. Dimensions of the device - 420 x 580 x 720 mm. The seat is at a height of 380 mm. The weight of this dry closet is 5 kg.

For normal operation it is necessary drainage system and ventilation. For the latter, use a ventilation pipe with a cross section of 10 cm.

Dry closet Compact-M
The manufacturer of the Compact-M model is Tandem LLC. Its body material is low pressure PE (HDPE), the upper part is polystyrene. It does not have a detachable waste container. It is replaced by the base of the toilet

The tank is quite roomy, so waste can be cleaned once a month. You can install in the house or in a non-residential annex. There are special handles on the case for moving.

# 2: Tandem Compact Eco Features

This model is the same stationary dry closet with a dry flush, but with a slightly large storage tank - 70 liters. The design with a polyethylene housing can withstand a load of a maximum of 180 kg. The height of her seat is 450 mm, dimensions - 520 x 710 x 720 mm.

Dry closet Compact Eco
The Compact Eco housing is made of polystyrene, which is shockproof. The design consists of two parts: the cover and the base. A tank with peat and a lever for dry flushing is located behind. A seal is placed between the base and the cover

A storage tank with a separator is placed inside the base. Both of these parts are made of plastic. Liquid and solid waste are separated by a separator. To do this, it has special openings on the bottom and bottom of it, through which liquid flows and enters the storage part of the structure. The solid part of the waste remains in the separator.

# 3: Dry closet Piteco 506

The design is small in size - 390 x 590 x 710 mm, weighs 20 kg. The seat is at a height of 420 mm. The upper tank has a volume of 11 liters, the cumulative is four times more - 44 liters. The maximum allowable load is 150 kg.

Dry closet Piteco 506
The Piteco 506 case is made of PP. Equipped with a direct-flow ventilation pipe. The waste container has three convenient handles

The pipe included in the kit has a length of 3 m. In addition to it, the set has couplings - 3 pcs., A two-meter drainage hose with a clamp and a seat with a cover.

# 4: Dry closet Piteco 905

In its lineup, this dry closet is the most spacious. With rather modest dimensions - 59.5 x 82 x 80 cm, the storage tank holds 120 l, the upper tank - 30 l. The height of the toilet is 48 cm, the weight is 12 kg.

Dry closet Piteco 905
The volumetric tank has wheels. In combination with recesses-handles on the walls, this provides convenient transportation. The maximum load is 150 kg

The tank is connected to the drain through a fixed base platform.After disconnection, the outlet is sealed by an automatic valve. During the removal of waste, the ventilation pipe is disconnected from the housing.

# 5: Toilet Bioecology Ecolight Summer Resident

Ecolight toilets are produced by the Bioecology company. This is a stationary cabin equipped with a storage tank that holds 225 liters. Dimensions of the structure: 1.15 x 2.3 x 1.15 m, weight 60 kg.

Dry closet Ecolight Summer resident
The cabin of the dry closet Ekolayt Dachnik consists of four profiled enclosing side structures, a translucent roof, and a door with a latch. Reinforced pallet included

The toilet cabin is made of polyethylene - shockproof and fireproof. The set is supplemented by an exhaust pipe, a comfortable seat with a lid. For bags inside the cabin there is a special holder.

Unpleasant odors and harmful fumes are neutralized by the ventilation system. Installation and dismantling of the structure is easy, and for its operation there is no need for sewage, water supply and power supply.

What is a chemical dry closet?

This formulation corresponds to a portable street booth, a room mobile toilet, and a unit consisting of several cabins, where waste accumulates in the receiving tanks. The role of "orderlies" is played by chemical concentrates based on formaldehydes.

They neutralize the smell, prevent the multiplication of various fungi and microbes, thin the waste. For this reason, the prefix “bio” does not sound quite right here.

Considering the features of such a dry closet and how it works, we can conclude that the waste processed in it cannot be called environmentally friendly. Therefore, composting and applying them is not recommended.

Profitability is their main advantage - for 1 liter of waste only 5 ml of “chemistry” is needed.
Structurally, these are two containers in contact with each other. In the upper tank is water. It is necessary for washing off. The lower tank is designed for waste recycling.

Smells and liquids do not burst out due to the presence of a sealing valve. More advanced models have an indicator. It gives a signal as soon as the tank is full.

Chemical dry closet
After filling the lower tank of the portable chemical dry closet, it is disconnected and all contents are poured out of it. For this, a special place

So, a container with a volume of just over 20 liters needs to be emptied every seven days, provided that the family of three people uses the toilet. This option is very convenient when the family has a bedridden patient.

A toilet of this design in this case can be placed under the bed. At the same time, as the manufacturers assure, there will be no unpleasant odors in the apartment.

Popular chemical toilet models

Among the most popular chemical dry closets, the following models can be noted:

  • Thetford Porta Potti Qube 365;
  • Enviro 20;
  • Mr. Little Ideal 24;
  • Ecostyle Ecogr;
  • Bioforce Compact WC 12-20VD.

Different design differences between different models do not. The difference in the volume of the storage tank and the availability of additional options.

# 1: Thetford Porta Potti Qube 365 Dry closet

This portable model is the most popular among chemical dry closets. Consumers are attracted by light weight (4 kg), compactness (41.4 x 38.3 x 42.7 mm). At the same time, the lower tank is designed for 21 liters, and the upper one for 15 liters. The distance from the bottom to the seat is 40.8 cm. According to its parameters, this is the best option when caring for a disabled person.

Dry closet Thetford Porta Potti Qube 365
Flushing with water in this dry closet is carried out by means of a piston pump. Without emptying, the tank will withstand approximately 50 cycles of use. Three people can use it for about a week

The indicator will indicate the need for maintenance. The lower tank is removable, there are handles for carrying.

The negative point is the considerable cost of the drug that breaks down waste.

# 2: Enviro 20 dry closet

The model is an economical option. It is made in Canada and can be a good solution for travel, for caring for the disabled. The volume of the upper tank is 10 liters, the bottom - 20 liters. By means of latches, the tanks are fixed motionless with respect to each other.

Dry closet Enviro 20
The dry closet is easily cleaned with a hand pump. The case is made of frost-resistant material (polystyrene) and supplemented with a corrosion-resistant coating. Drain valve prevents fluid leakage and odor seepage

Structurally, the sanitary system is designed so that the storage tank is easily emptied. Filling the flushing tank also does not create problems. There is also a filling indicator.

# 3: Mr. Toilet Little Ideal 24

"Mr. Little" is designed for a large family - 4 - 7 people. Its dimensions are 42 x 41 x37 cm. The tank holds 15 liters of water for flushing. The waste container can be filled up to 24 liters. There are indicators on the receiving tank and the water tank.

A piston pump is integrated in the flush system. The sanitary device works in the temperature range from +1 to + 40 degrees.

Dry closet Mr. Little Ideal 24
Mr. Little weighs 4.6 kg. At the same time, it can withstand a load of up to 250 kg per case and 30 kg per cover. Withstands outside temperatures from - to + 40⁰

Special liquid is poured into the tank, which is located below. Waste splitting lasts 10 days. A special handle on the storage tank, as well as a built-in removable nozzle simplify the disposal process. In addition, there is an air bleed valve on the housing.

Hidden guides and additional fasteners give this model additional stability. The plastic of which the construction is made does not absorb odors.

# 4: Model Ecostyle Ecogr

Chemical toilet Ecostyle Ecogr - a polyethylene toilet cabin resistant to ultraviolet radiation. The kit includes a front panel - a door and an arch made of steel frame. The structure is fixed by means of high-strength hinges to rivets made of steel. Inside there is a valve equipped with a busy indicator and a hook for things.

Dry closet Ecostyle Ecogr
The roof and side panels of this model have a modern design. The design looks aesthetically pleasing both in a summer cottage and in another territory

This dry closet weighs 80 kg. Capacious receiving tank - 250 l. In the cab there is a wooden pallet soaked in water-repellent. Cabin dimensions - 1.1 x 2.2 x 1.1 m.

# 5: Portable Bioforce Compact WC 12-20VD Model

The design is assembled from two compartments: the upper - 12 l and the lower - 20 l. In the first fill in the input for flushing. It is complemented by a pump, a seat with a lid. Waste is collected in the lower compartment.

There is a sliding valve that prevents odors and liquids. Overpressure is relieved by an exhaust valve. The level of waste is controlled by an indicator.

Dry closet Bioforce Compact WC 12-20VD

The model is designed for a maximum load of 120 kg. It has dimensions of 370 x 435 x 420 mm. The lower tank is removable

These chemical dry closets are made in Thailand. For their installation, additional ventilation and communications are not needed.

Features of the electric dry closet

This design is significantly different from the first two. The liquid from the electric toilet is discharged into the cesspool or into the sewer. Solid residues are sprinkled with disinfectant powder and dried or burned.

Waste in any case is very small. After they can be used as fertilizer. Among autonomous toilets, this design is the most expensive and requires constant power supply and forced ventilation.

Without this, odors arising from the burning or drying of solid residues cannot be avoided. Therefore, ventilation is a prerequisite.

# 1: Cinderella Electric Dry closet

Plumbing fixtures are produced in Norway. It is considered non-waste. There is no need to connect water to it. The flushing process is carried out by means of a compressor connected to the mains.

Dry closet Cinderella
For the normal functioning of the electric dry closet, neither biological nor chemical means are needed. After the disposal procedure, the environmentally friendly mass

Waste incineration is carried out in a special container. After this, only 100% safe ash remains, from which the toilet is released twice a month. Such a dry closet works from a 220 V network.Ventilation is mounted through the roof or through the wall.

# 2: Separett Villa 9011 Electrical Toilet

This electric dry closet was launched in Sweden. Its distinctive feature is that you can even connect it to a car battery. The model works without connecting water. The liquid component of the waste leaves through a flexible hose, while the solid component in the 23-liter tank is dried and reduced in volume to 70%.

Electric toilet Separett Villa 9011
The Separett Villa 9011 housing is made of impact-resistant material, therefore it is resistant to abrasions and scratches. The plumbing fixture is equipped with a comfortable polypropylene seat. The kit has all the details for installation

In order for the fan to work, it is connected to a voltage of 220 V. A seat for children is also included in the kit. The only negative is the mandatory ventilation device.

For some, the inconvenience is the fact that you can use the device only in a sitting position. This is explained by the fact that the back of the container in which the waste is collected opens only under the weight of a person.

# 3: Dry closet BioLet 25

This stationary electric dry closet with a body made of ABS plastic is made in Sweden and can accommodate 3 people. Equipped with a fan, automatic compost mixing function. Dimensions of sanitary ware - 550 x 650 x 710 mm. Height from base to seat - 508 mm.

The power consumption of the plumbing system is 20 - about 5 watts. The kit includes the actual toilet, pipes, catalyst. For correct operation, an exhaust system is required.

Scheme of the dry closet BioLet 25
Inside the structure, all biomass must be in a homogeneous state. To do this, compost and waste are regularly mixed by automatically turning on the mixer. Turning on occurs when raising and lowering the cover. At the same time, oxygen enters

During mixing, some part of the dry processed product wakes up in the pan through the grate. Compost mass is blown by the fan. Vapors and odors escape through the ventilation system. In case of accumulation of excess liquid, the float switch automatically drives the air blower into operation.

The thermostat can also adjust the liquid level manually by adding or lowering the degrees inside.

Recommendations for future buyers of the dry closet

When choosing a suitable dry closet, you should be guided by several criteria:

  1. Simplicity of design and convenient operation.
  2. Hygiene, ability to retain unpleasant odors.
  3. Stability, durability, high-quality assembly.
  4. Convenience of service.
  5. Volume of the tank. It must match the number of residents.
  6. Seat height. The optimum size is 400–460 mm, but the presence of children must also be taken into account.
  7. Presence of seat heating function and capacity indicator.

For operation in a country house, it is advisable to purchase a portable plumbing system. In summer, she can be on the street, in winter - in the house.

It is better if chemistry is not used in the selected biotulet. Then the recycled waste can be used as fertilizer.

If the model is electric, then where it is to be operated, there should be no problems with power supply.

Dry closet selection
And in a country house, and in urban housing, bio-nitaz should be comfortable, convenient. They buy it for a long period, so plumbing should be of high quality and durable.

For an apartment, a stationary option with a good design is better. If finances allow, you can install an electric model with many functions. You need to calculate the volume of the tank, the frequency of its emptying depends on this.

If the money to buy a dry closet is not enough, you can build it yourself. And how to do this can be read in this stuff.

Conclusions and useful video on the topic

Proper use of the dry closet:

Choosing the best option of dry closet:

In places where the benefits of civilization have not yet reached, perhaps there is no more convenient design for the disposal of waste products than the dry closet.It is also a worthy way out of the situation when there is a bed patient in the house.

The main thing is to choose a device that is suitable for specific circumstances, meets all the requirements both in quality and in functionality.

Do you have a dry closet in the country? Please tell us which model you chose, what guided you with this, and whether you are happy with your purchase. Write your comments in the block under the article.


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Visitors Comments
  1. Ilona

    We installed a dry closet in the country a long time ago, because it’s easier to care for it than for a simple summer toilet, and it looks much better. This type of autonomous plumbing is more convenient and comfortable in operation. For all this, it can also be used in the winter, in contrast to the summer street, in which it is very cold in winter. I believe that a dry closet is the best option for a summer cottage, until a stationary one is established in the house.

  2. Marina

    In summer, we have a dry closet in a box that was built for an outdoor toilet, and in the autumn-winter time we bring it into the house in a combined bathroom, in which pipes are not connected to the stationary toilet. There is almost no smell from the dry closet, but we use peat. In the city I can’t go to plastic dry closets because of the terrible smell and look. The dry closet for our summer residence is a temporary phenomenon.

    • Semen

      Do you have a dry closet with a fluid outlet? Which brand? It’s just that we also use peat in the country, but the smell emanates from it quite noticeable. And often, not only the smell of lush grass.

      • Expert
        Nikolay Fedorenko

        If you are not satisfied with the odors from a peat toilet, then I can recommend an alternative inexpensive solution. This is Thetford Porta Potti 165, cost about 80 dollars. The dry closet consists of two parts, upper and lower.

        For each part, a separate liquid is needed: in the lower blue, in the upper pink. For 100 ml of chemistry, you need 3 liters of water, fill through a special technical hole. Such a toilet can be used even in the house, there is no smell from it.

        If you buy the original chemistry from the manufacturer Thetford, then it comes out quite expensive: about $ 40 for two bottles. As an alternative, I can offer Master WC Rinse 1 liter + Blue 1 liter liquid kit for just $ 6. There is practically no difference in principle and quality of action.

        Attached photos: