How to choose pipes for water supply: types, features, which are better

When planning a scheme for arranging water communications in a house, the most problems arise not with the placement of consumers or the calculation of water consumption, but with the choice of characteristics and material of pipes for water supply. There are many options, each with its own advantages and disadvantages.

Many of the nuances of pipe selection are so specific that you can only learn about them from your own experience and after several years of operation.

Nuances of choosing pipes based on material

Steel water pipelines are gradually becoming obsolete. With rare exceptions, the wiring of water supply pipes is made of plastic or metal-plastic.

It is cheaper in materials and labor, since high-quality steel is expensive. In addition, you will have to use at least one electric and gas welder, and this is also an expense.

Plastic and metal-plastic water pipes, in addition to being cheap, have their own disadvantages and features. Therefore, when selecting pipes, you need to take into account the following requirements (in descending order of importance):

1. Compliance of the pipe material with the requirements for certain water supply conditions.
2. Durability of the pipe material, the ability to maintain and repair the water supply system at lower costs.
3. The price of pipe blanks, the availability of material in the future for replacing (if necessary) individual sections of the water supply system, inserting new taps, valves, filters, meters.
4. Availability for in-house assembly.

Laying water supply pipes yourself is a good way to save on the services of a professional. But many apartment owners prefer to choose a water supply arrangement on their own in order to be sure of proper assembly.

Modern technologies for assembling metal-plastic and plastic water supply pipes do not require long training in installation methods or complex equipment. It is enough to master soldering polypropylene or installing fittings, and choose the right tools and devices for installation.

Polypropylene pipes

A special feature of polypropylene pipe blanks is their predisposition to soldering (welding). Almost the entire range of polypropylene pipes is cast from a melt mass consisting of several types of polymers.

Depending on the proportions and additives, product characteristics may vary. But in any case, all brands can be easily soldered with an electric soldering iron, which ensures a strong monolithic seam.

Most apartment owners choose polypropylene only because this type of workpiece can be easily soldered on its own.

Conventional PP pipes, depending on the wall size, can withstand pressures of up to 35 bar. All types of PP pipes can be used to assemble home water supply according to the sanitary and hygienic requirements of SANPiN.

For the manufacture of water supply systems, PPR grades, random copolymer, are usually used.You can choose complex reinforced ones - they are more resistant to heat, therefore they are used mainly for heating systems. Pipes made of pure polypropylene are used mainly for supplying drinking water in low-pressure water supply systems.

The only significant drawback of polypropylene water supply systems is that polypropylene has a high coefficient of thermal expansion (0.15 mm/m*K), so the wiring must be done with loops or adapters that compensate for the elongation of pipes when heated.

Metal-plastic pipes

Aluminum-polymer water pipes are a rather complex structure. The metal-plastic pipe itself consists of three layers of different thicknesses:

1. The inner layer is low-density polyethylene.
2. The second layer is aluminum foil with a thickness of 0.6-1.1 mm. Provides rigidity and strength of the metal-plastic pipe. Withstands pressure up to 16 bar.
3. Outer layer made of PE or PEX polyethylene. Protects aluminum from air oxygen and condensation.

Craftsmen usually suggest choosing metal-plastic in cases where water supply needs to be organized in the shortest possible time.

Polymer-aluminum water supply systems have been used for a long time, more than two decades. During this time, we have accumulated extensive experience in the practical use of metal-plastic pipes.

The durability of the material is high. Metal-plastic from well-known manufacturing companies can be used for 20-25 years, even in hot water supply conditions. It is often recommended to be chosen for wiring a water heating circuit due to its low coefficient of thermal expansion.

But if you choose low-quality metal-plastic pipes, then the water supply systems fail after 2-3 years of service.

There are only two drawbacks:

1. Metal-plastic cannot be welded or soldered. Water supply or heating pipes are connected only with compression fittings, which increases the cost of the water supply system. The type of fitting will need to be selected immediately, depending on the pressure and temperature of the water.
2. You will need to buy or rent a special tool - pliers or a sediment press.

The main advantage of metal-plastic is the ability to disassemble and reassemble the water supply system, change individual pipes, and repair water fittings. It is possible, using adapters, to make a water supply circuit consisting of pipes of different materials.

Polyethylene pipes (HDPE)

The water supply system is more durable and resistant to mechanical stress. Therefore, polyethylene water pipe is used mainly in pipelines operating under load.

Pipe blanks made of polyethylene are designed for a lower operating water pressure than in the case of polypropylene. Typically up to 16 bar. At higher loads, 20-25 bar, the pipes may expand or deform in outer size.

The point here is not the tensile or bending strength of the material. Most water systems are assembled by welding. At the same time, polyethylene has lower weldability (due to the inertness of the material and poor adhesion in the melt).

Therefore, high-capacity water supply systems with a diameter of 50 mm and more are assembled by welding. In home plumbing, assembly is performed using sleeve fittings and a hand press.

The high chemical resistance of HDPE does not mean that any polyethylene pipes can be used for home water supply. For drinking water, products manufactured in accordance with GOST 18599-2001 are selected.

They are usually blue or black with a blue stripe. All that is done in accordance with GOST R50838-2009 is polyethylene pipelines for pumping gas (black color, yellow longitudinal stripe).

The coefficient of thermal expansion of HDPE is approximately the same as that of polypropylene. Since the rigidity of the PE pipe blank is lower, the pipes can be deformed even at low hot water temperatures.

What pipe diameter to choose for water supply

For private households, the internal size of the supply pipe is tied to its length. It is believed that the longer the line, the higher the water pressure loss and the lower the flow rate. For example, such a division was selected experimentally for steel water supply lines.

For a section of up to 10 m, a diameter of 20 mm is sufficient, from 10 m to 30 m – 25 mm. For lengths greater than 30 m, a line with a diameter of 32 mm will be required. Using these recommendations, you can choose polymer blanks for water supply to a suburban area.

And even reduce it by 10%, since the inner surface of the “polymers” and metal-plastic is smooth. Losses will be lower than on steel lines.

The most correct approach is to choose the diameter of the plastic pipe blank, focusing on the maximum water flow of consumers connected to a given water supply line. It is enough to sum up the outlet cross-section on all connections and select the closest value of the plastic pipe according to the nomenclature.

Diameter of polypropylene pipes

Another option is to choose the diameter of the polypropylene water supply line based on the size of the old steel water supply pipes. Often, during renovations, apartment owners take measurements from the old water supply and transfer the diameters to the new pipes. The approach is correct if the old water supply system met the needs of the residents.

But there are two important points to consider:

1. The pressure in the water supply pipes should not change. If the riser and the central water supply valve were replaced with the old water supply in the apartment, then the result of calculating the cross-section will be overestimated.
2. It will be necessary to select a new diameter of the water supply pipe taking into account the change in inlet water pressure. For example, if the old riser had 2.5 bar, and after replacing it with a new one, it turned out to be 3 bar, then you can choose a workpiece with a cross-section that is 15% smaller.

Another nuance is that the systems for measuring the diameter of a steel pipe and a polypropylene pipe have differences. Steel blanks are produced in a standard range of diameters.

For domestic water supply systems these are 15 mm, 20 mm, 25 and 32 mm. In inches, ½”, ¾”, 1” and 11/4” respectively. In this case we are talking about the internal diameter.

For polypropylene pipes, the measurement is carried out by the outer diameter. In marking, wall thickness is added to the size.

To recalculate you will need:

1. Measure the diameter of old steel water supply pipes.
2. Determine the standard internal size from the range of nomenclature.
3. Select from the table a polypropylene blank with a recalculated internal size (subtract double wall thickness).

Calculations may not match. In this case, experts recommend taking a PP pipe from the series with the closest diameter, provided that the reduction in size is no more than 10%.

Diameter of metal-plastic pipes

The performance characteristics of metal-plastic are higher than those of polypropylene or polyethylene. For example, the magnitude of the destruction pressure at room temperature. For a metal-plastic water supply with a transverse dimension of 16-26 mm, it reaches 90 bar - much more than in the case of plastic water supply pipes.

This means that with proper assembly and high quality water, metal-plastic should last longer than PP or PE. Manufacturing companies claim a lifespan of 50 years, although in reality the water supply system will last no more than 30.

The use of metal-plastic water pipes has one important advantage. The core of the pipe billet is aluminum and is not subject to structural changes over time, under the influence of water or temperature.

The aluminum part will ensure the strength and load-bearing capacity of the water supply system even after 100 years (if there is no contact with water). In polyethylene and polypropylene, the material ages due to the residual effect of the catalysts remaining in the polymer mass. Therefore, the service life for PP pipes and HDPE pipes will be lower in any case.

The diameter of the pipe blanks can be selected based on the typical wiring diagram for a metal-plastic water supply system.

For private houses and apartments, owners usually choose a collector wiring diagram.

Diameter of polyethylene pipes

Polyethylene-based water supply systems are becoming increasingly popular; PE pipes are gradually being forced out of the market. Apartment owners try to choose HDPE pipes and install polyethylene water pipes for 3 reasons:

1. The reputation of low-pressure PE pipes as the safest for drinking water according to hygienic standards.
2. Simplification of the technology of welding and joining of polyethylene blanks.
3. HDPE grade polyethylene is distinguished by the fact that there are practically no deposits of rust, silt, or debris on the inner surface of the water supply system. This means that you can immediately select a workpiece of the required diameter, without adjusting for silting of the flow area at the welding or brazing sites.

For polyethylene water supply systems, the required diameters can be selected based on the total and individual water consumption of each consumer.

How to choose polypropylene pipes for water supply

On the building materials market you can find a huge amount of imported and domestic PP water pipes. Pipe polypropylene from the Italian company Valtec is considered the best.

Slightly cheaper, but of good quality, are PP pipes from the Czech company “FV-Plast” (trademark “FAZER”), Turkish “Kadle”. For lovers of German building materials, we can recommend the brands “Watertec” and “Climatec”.

To enter the house from the pump to the accumulator, it is better to choose pipe blanks with a diameter of at least 32 mm. But the water supply system will work properly even if you choose 24 mm.

But only the first 5-7 years. Further, as sludge is deposited on the welded joints, the throughput will decrease, so it is better to take a workpiece with a reserve.

To enter the apartment, you can choose 24 mm - the water in the city network is purified of organic matter, so there will be no acidification of the water supply.

Typically, experts recommend choosing PPR brand PP pipes for domestic water supply systems. To install water supply inside the house, pipe blanks of class PN10, designed for operating pressure up to 10 bar, are sufficient. For areas of water supply with high pressure, for example, from the pump in the well to the upper filter, it is better to choose a PP pipe with class PN30.

Another nuance is that the durability of polypropylene water pipes depends on the water temperature. For hot water supply, it is recommended to choose reinforced products based on a heat-stabilized polypropylene matrix PP-RCT and fiberglass.

Which metal-plastic pipe to choose for water supply

It is more difficult to choose metal-plastic for water supply lines, since the quality of the workpiece largely depends on the quality of welding of the aluminum sublayer. It is impossible to see the seam, but you can try to evaluate it by cutting the workpiece, but this is also a rather risky method. The only option is to choose a metal-plastic pipe from a well-known brand, for example, the Italian “Valtec” or the German “Oventrop”.

Communications made of metal-plastic pipes with a diameter of 26-32 are most often used for entry into the house or for the central riser of high-rise buildings. Sometimes it makes sense to choose 26 mm blanks in a situation where the inlet pressure is low, 1-1.2 bar, or for routing channels according to a heated floor scheme.

To enter the house, 26 mm is enough. If you make water supply inside your home using a collector circuit, then for each consumer it is enough to supply a 16 mm line for the mixer on the bathtub or washing machine.

For the rest of the wiring, you can choose 12 mm communications. This is more than enough for normal water supply even at maximum load.

Up to 70 liters of water passes through this cross section per minute, and the flow rate is limited only by taps and valves. If the pressure in the water supply is at least 3 bar, and you select a diameter of 26 mm for the input, then at any tap the water flow will be at least 12 l/min.

What to pay attention to

The desire to choose pipe material of a larger diameter with thick walls is quite understandable - plastic and aluminum, although they look modern, are somehow not particularly reliable. No one wants to put clamps on a fistula or an accidentally damaged wall.

But experts advise choosing pipes with a diameter of no more than 20 mm. The reason is that metal-plastic communications will have to be bent at turns or at supply lines to the consumer.

This will require considerable physical effort. In addition, for MP pipes there are restrictions on the minimum arc radius.

The larger the diameter, the smoother the bend should be. This is important, especially when the water supply system is planned to be laid in boxes under plaster.

Purchasing large-diameter pipe blanks for water supply means the need to choose more expensive fittings. Moreover, on a hot water supply system at the connection points it will be necessary to periodically, once every 4-5 years, crimp the fitting to compensate for the compression of the gasket.

Which water supply pipes are best to choose from polyethylene?

The question often arises about the advisability of using polyethylene communications, if you choose metal-plastic and polypropylene, which have been repeatedly tested in practice. Polyethylene better tolerates mechanical load, lateral pressure, bending, twisting, and freezing. Therefore, it makes sense to choose polyethylene communications for laying water supply systems in difficult conditions.

To supply water, two grades of polyethylene pipes are used - PE80 and PE100. The properties are almost the same, except that the first has less tensile strength, the second is able to withstand high tensile stresses at increased pressure.

You need to choose a pipe for water supply taking into account dimensions and design pressure. Therefore, in addition to the polyethylene grade, the SDR index is used. This is the ratio of the diameter to the wall thickness; the index helps you select a pipe based on strength and maximum (working) pressure.

PE 80 SDR 21

This type of pipe blank is used for arranging cold water supply communications. The SDR=21 index is quite large, which means the wall is relatively thin.

The pipe is weak, withstands pressure no more than 8 bar. You can choose for underground water supply provided that communications are laid on a prepared pad. The temperature of polyethylene should not exceed 40℃.

Suitable for non-pressure sewerage of residential premises. The minimum diameter of PE 80 SDR 21 is 40x2 mm. The average price per linear meter is 54-55 rubles. You can choose to install a section of water supply from the adapter to the inlet into a one-story house.

PE 80 SDR 17

Working pressure – 10 bar. It is used for drinking water communications indoors or for laying in the ground to a depth greater than the soil freezing level. Can be chosen for laying irrigation systems. Since the pipe is made of PE80, there are heating restrictions of no more than 40 ℃.

The minimum size is 32x2 mm. The average price is 42 rubles/m. P.

PE 80 SDR 13.6

Designed for a working pressure of 10 bar. You can choose to install water supply inside a residential building or cottage. It is often used for laying temporary communications for pumping water from pools, ponds, and reserves in tanks for watering plants.

The minimum size is 25x2 mm. The average price per linear meter is 32 rubles.

PE 100 SDR 26

Despite the high SDR, this type of pipe is highly durable. Thin walls can withstand pressures of up to 6.3 bar. And only due to the fact that weaving polyethylene has greater density and rigidity.

PE 100 SDR 26 is used to make low-pressure and high-performance water pipes. You can choose for sewerage in a bathhouse, summer kitchen or country house. The minimum size is 50x2 mm. Average cost – 65 rubles/m.p.

PE 100 SDR 21

This type of pipe blank can withstand pressure up to 8 bar.It is somewhat inferior to the PE 80 SDR 17 and PE 80 SDR 13.6 brands in terms of bursting load, but, unlike its competitors, it has greater stability. Can be chosen for water supply systems that are constantly under load.

Minimum diameter – 40x2 mm. The average price is 52 rubles/m. P.

PE 100 SDR 17

Pipes of this brand can be chosen for wiring the main lines of the water supply system in a house or apartment. Water pipes made from PE 100 SDR 17 are more reliable than when using PE 100 SDR 21.

Maximum pressure – 10 bar. The average price per linear meter is 42 rubles.

PE 100 SDR 11

High strength pipe blanks are typically used for water mains with a pressure of 16 bar. You can choose to connect a pump in a well or supply water to a house at a considerable distance from the water source and with a large difference in elevation of the terrain.

This brand of pipe is popular among apartment owners due to its low cost and simple soldering technology. The minimum diameter is 20x2 mm, the average price per square meter is 26 rubles.

To choose the right pipes for water supply, you need to know exactly the characteristics of the future water supply, flow and water pressure. And also take into account the associated costs of purchasing tools, fittings and consumables.

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