Measure the water pressure in the apartment yourself

About water pressure and its measurement - theory

Water pressure or its pressure, in theory, shows how much a column of water can be raised from the point of its measurement. Water pressure is measured in bars. 1 bar of water pressure can lift its column to a height of 10 meters. In relation to water pumps, a 3 bar pump, under ideal conditions, can lift water from a depth of 30 meters.

A device for measuring water pressure at any required point in a water supply network is called a pressure gauge. It is round in shape with a scale in bars and an arrow. To connect the pressure gauge, it has a special input fitting with an external thread.

Note: It is important to understand that water pressure in a plumbing system decreases as water moves through the pipe. A number of factors influence this decrease:

Pipe wall resistance,
Pipe turns;
Narrowing and expanding the diameters of water supply pipes;
Slopes and ascents of the route.

Read: The whole truth about ball valves that you need to know

Accuracy of water pressure measurement in the absence of a device

The accuracy of calculations of water pressure in the pipes of a house will depend on the exact physical data of the pipeline.

If the real characteristics are measured as accurately as possible, then the mathematical calculation will be quite accurate.

Approximate data will provide the opportunity to calculate pressure only at an approximate level.

Knowledge of water pressure standards will allow you to move on to the practice of measuring water pressure at home. Next, 3 methods are discussed on how to calculate pressure readings without a pressure gauge.

Where to measure pressure

Considering the factors influencing the decrease in water pressure in the water supply system, it is important to understand that the water pressure at the entrance to the apartment may differ from the water pressure at the water intakes. Most likely this change will be minor, but it will happen.

Therefore, in order to dispute with the management company, you need to measure the water pressure at the water supply inlet to the apartment. To study the connection conditions for a new household or plumbing appliance, you need to measure the water pressure at the connection point of this device.

For example, you want to buy a washing machine that can only operate at a water pressure of 1.6 bar. Ideally, water pressure should be measured at the washing machine connection point, and not at the water supply inlet.

How to check using the flow method?

You can make calculations using tables of values, but the result will not be accurate.

Therefore, the best option would be to carry out calculations on site, taking into account the speed of water flows, the material of the system pipeline, and other properties of the pipeline.

The simplest formula for calculating the fluid consumed will be:

Q=П*d^2/4*v , where:

Q is the water flow rate we are interested in (liters per second).
v —flow velocity (m/s).
d – pipe diameter (in cm).
P - "Pi number" - a constant from mathematics, approximately 3.14.

For example, there is: d=4, v=2. In this case: Q=3.14*4^2/4*2=3.14*8=25 liters per second.

This formula can be used when searching for other unknowns. In the case when the diameter along with the water flow rate is known, its speed can be determined. Or, if the speed is known and the flow rate is known, the diameter can be calculated.

Three methods to independently measure the water pressure in an apartment

Let's look at three ways to independently measure the water pressure in your apartment.

Method 1, permanent

If you install pressure gauges in the inlet water supply unit, you will be able to constantly monitor the water pressure in the DHW and cold water systems. Water pressure will be measured precisely at the water supply to the apartment.

Pressure gauges are installed on hot and cold water supply, after the main shut-off valves of the apartment, after the coarse water purification filter, after the check valve, BEFORE the water consumption meters.

Read: For a novice plumber - basic rules and some tips

If the water supply system has fine filters, then it is better to place pressure gauges after them, or even better to buy thin filters with pressure gauges.

several pressure gauges in the unit

It is important to note that usually, to save space and ease of installation, pressure gauges are supplied complete with pressure reducers.

pressure gauge with pressure reducer

Note: installing a pressure reducer does not require installing a pressure gauge and vice versa. It's just convenient.

Increasing pressure in the water supply

Much more often, the need to increase the intensity of water flow appears on the upper floors of high-rise buildings or in suburban buildings connected to water towers.

Advice: before using drastic measures, first check the reliability of the pipeline for clogging, since a decrease in the internal passage due to accumulation of debris also causes a drop in pressure. In this case, either cleaning or replacing the pipes will help.

The instructions offer a choice of three methods to solve the problem of low pressure.

Method No. 1: circulation pump

It is possible to purchase and install a circulation pump in the system in front of the water intake point, which can more intensively draw water from the pipeline, increasing the flow. This is a fairly economical and effective option, but it is only possible if there is at least water in the pipes.

According to the operating mode, the pumps can be:

Manual. Relatively inexpensive models that need to be monitored during their operation and periodically turned off so that they do not burn out.
Automatic. More expensive, but completely autonomous samples.

Method No. 2: pumping station

This equipment consists of three elements:

A centrifugal pump that supplies increased flow power in the system.
Hydraulic accumulator with a volume of up to three cubic meters.
A pressure switch that controls the entire structure.

A particular advantage is the ability to supply a pressure level of up to 4 atmospheres, even in the event of periodic shutdowns of the water supply. The fact is that as long as there is an inflow, the pump works, accumulating the tank, and after that the device distributes the liquid through the pipes to the points of consumption.

Cons to consider:

High price.
Enormous dimensions.
The need for periodic cleaning of the hydraulic accumulator.

Method No. 3: autonomous water supply

A well with water-lifting equipment is a very costly and labor-intensive task, moreover, its implementation is likely only in suburban areas. But under such conditions, you will not only determine the pressure level in your water supply system yourself, but will also gain complete independence from the public water supply with its constant interruptions and low-quality water.

Method 2, an accurate research method to measure water pressure in an apartment

For this method, you need to make a control device to measure water pressure.

It is not always possible to install pressure gauges in a previously assembled apartment water supply unit. In this case, as well as to measure the pressure at the water intake, you need to make a simple control device.

To make it you will need:

Pressure gauge at max. pressure 10-25 bar.

It is important to understand here that pressure gauges may have different connecting threads.

According to GOST 2405-88, pressure gauge fittings must have metric threads (Appendix 4, Table 12): M10x1 (D scale diameter = 40 mm), M12x1.5 (D scale = 50, 60, 63 mm), more often M20x1.5 ( D scale = 100, 150, 160 mm).

If you have a pressure gauge with an M20x1.5 thread, to connect it you will need an adapter from a metric thread M20x1.5 to an inch pipe thread G½.”

For ease of connection, you may need an extension cord G½" HV (internal thread - external thread). If you have to screw the pressure gauge onto a water socket with an external thread, then you need an extension G½" BB (internal thread - internal thread).

Next, you need to assemble this device, be sure to use a linen seal or FUM tape. After assembly, you can independently measure the water pressure in the apartment in any desired place.

Read: Distribution manifolds without taps

connecting a pressure gauge via a tee

Tip: To get a more accurate water inlet pressure, measure the water pressure at the water outlet (or pipe) supplying water to the toilet. As a rule, it is located closest to the distribution node.

Method 3, a very approximate method for measuring water pressure in an apartment

If you want to qualitatively assess the inlet pressure at the “good-bad” level, try timing the time it takes for the container to fill with water.

For example, take a 3-liter saucepan. Fill it with water when the cold water or hot water tap is fully open and measure the time for complete filling.

If the filling time of a 3-liter container is more than 8 seconds, the water pressure in the system is less than the standard 0.3 bar. In this case, the tap should not have an aerator (mesh), and the pipes should not have narrowings along the route. Narrowing the pipeline significantly increases the speed of water movement and such measurements will be incorrect.

Calculation of pressure through flow

To make approximate calculations of the pressure in the pipeline, you will need a two-meter transparent hose. We put one end of it on the water tap, after which we turn on the water for a short time. But before starting the experiment, we perform two steps:

We plug the free end of the tube with any plug of suitable size.
We install the hose so that the water level inside it coincides with the point of its exit from the water tap - the so-called “zero level”.

The installation we assembled is a hydraulic pressure gauge. After this, turn on the water at full power. After a short time, a new water level will be established inside the hermetically sealed hose. Then you will need to record the following indicators:

The total distance from the zero level to the end plugged.
The length of the hose between the pressurized water level and the plugged end.

After this, you can calculate the approximate pressure in the tap using the following formula:

P = Ratm. x No/H1 In this formula, P means the pressure in the water supply system, Patm. – pressure before water supply, But – initial height of the air column, H1 – height of the air column after the tap is fully opened.

You can also calculate the approximate pressure by performing a series of mathematical calculations. You will need to arm yourself with a three-liter jar and a stopwatch. We open the water at full power, then place the jar under the stream and turn on the time countdown.

This method has significant errors and is very approximate. However, we can confidently say that if a 3-liter container is filled in more than 10 seconds, then the pressure in the tap is significantly lower than normal. If the pressure meets the established operational and technical standards, the jar should be completely filled in 5-7 seconds.

Consequences of non-compliance

Any deviation from the standard - be it more or less - has a negative impact.

If the indicators are insufficient, difficulties arise:

with connection and subsequent operation of household appliances (washing machine and dishwasher);
using showers, Jacuzzis, bidets, hydromassage devices;
with flush toilet;
with watering crops (in the private sector it is impossible to organize the process at a water pressure below 3.5 atmospheres);
with the functionality of a private heating system (minimum requirements for boiler operation: 1.5 bar; the average device operates at 3 bar).

If the pressure significantly exceeds the norm, this may lead to wear and tear of the elements of the water supply system , failure of devices connected to the water supply network and irrational consumption of water with a subsequent increase in bills for the service. Additional side effect: taps “whistle” when feeding. The phenomenon causes discomfort during prolonged showers and baths.

Reference! For most plumbing fixtures, pressure above 4.5 atmospheres is critical. Breakdowns resulting from strong pressure are not covered under the warranty card.

Computational and experimental methods

Determining the network pressure is possible not only with the help of specialized instruments, but also with the use of home-made devices and calculation formulas of hydrodynamics. An example of computational and experimental methods is the determination of pressure using a hose and the calculation method through water flow.

Water pressure regulator diagram.

In other words, a hydraulic calculation of the existing system must be carried out with sufficiently large assumptions to omit:

hydrodynamic resistance of individual sections of the pipeline;
mode of fluid flow inside the pipe;
pipeline material and length.

The results of such calculations and experiments will most likely differ in a significant amount of error and be of a qualitative (reference) nature.

Why is the pressure low?

Before you begin installing auxiliary equipment to increase the pressure of cold water, you should find out why there is low water pressure in your home. There may be several reasons. Some of the most common:

Contamination of pipes with hard deposits and debris. To fix the problem, you should clean the risers, and in case of large-scale blockages, replace them.
Contamination of the coarse filter device. To correct the problem, you need to clean or replace the special mesh on the filter.

If neither the pipes nor the filter are clogged, ask your neighbors if they are experiencing similar difficulties with water: if the answers are positive, then there are problems at the general distribution station, and if negative, then specifically in the pipe distribution of your apartment.

Pump installation diagram

And only after you are absolutely sure that the problem of low pressure is of an exclusively local nature, that is, it concerns your home specifically, and is not associated with any contamination of the pipeline, can you proceed to active actions to increase the pressure of the cold water supply.

We purchase a pumping station

This is serious pumping equipment that is installed in large private houses and cottages. It is used if the pressure is critically low or there is no water in the pipeline. Pumping stations consist of a device that pumps water and an additional container. It contains the amount of liquid that the residents of the house consume during the day.

Principle of operation:

After turning on the equipment, the pump begins to pump water into the container.
It continues until the pressure in the tank rises to 2 bar.
When the indicator is reached, the sensor recording the pressure sends a command to turn off the pump.
Now the whole house system begins to consume water from the filled tank. When it is empty, the process will repeat.

Such equipment can be installed in the basement, utility room, hidden behind decorative protrusions in the bathroom, etc.

SNIPs and GOSTs

Issues related to the water supply system have been reviewed and recorded at the legislative level. Regulatory documents:

SNiP 2.04.02-84 (indicators for a one-story building: 1 bar; with each subsequent floor the value increases by 0.4 bar);
Decree of the Government of the Russian Federation No. 354 dated 05/06/2011 as amended on 07/13/2019 (cold water pressure at the water intake point should be within 0.03-0.6 MPa, hot water - within 0.03-0.45 MPa) .

The second document contains information about the need to recalculate the cost of utilities when pressure deviates from the norm by 25%.

Conclusion

We looked at how to check the pressure in the water supply system and increase it if necessary. Each method has its own characteristics, so the choice should be made individually according to your situation.

Full power shower

The video in this article will introduce additional materials. Monitor the pressure level in your water supply.

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What should the pressure be in practice?

The fact that the minimum pressure may be 0.3 atm does not mean that this indicator is sufficient for full use of cold water. No household appliance will simply function at such a low pressure, so even if in theory you are absolutely within the norm, in practice things may not be so attractive.

Any standard apartment has a lot of household equipment that works with water: from a washing machine to a jacuzzi. These devices, depending on the power, put forward their own requirements for the incoming water pressure:

dishwashing and washing equipment – 2 atm;
heating boiler - 2.5-3 atm;
shower with hydromassage – 3.5-4 atm;
jacuzzi – 4 atm.

Advice. When buying household appliances, choose a model with a small pressure reserve - about 1-1.5 atm - this will allow it to withstand potential water hammer without problems.

Practice shows that the optimal cold water pressure for an apartment is 4-5 atm.

Authorities responsible for water supply

Before contacting any authorities regarding poor water pressure, you must make sure that the reason for this is not the device being clogged with lime or other deposits, equipment malfunction, etc.

If the reason is not the above, then if the pressure standards of the water supplied to the apartment building are not observed, you can contact the following organizations: Useful article If the management company does not respond to complaints in any way, you should contact higher regulatory authorities - the housing inspectorate, Rospotrebnadzor and the court. Read more in this article

to the management company (MC) on whose balance sheet this house is located. The management company, by definition, is an intermediary between the provider of life support resources for apartment buildings and the citizen who is the owner or tenant of housing in a given house. The following must be done:
take the complaint to the Criminal Code in 2 copies, leave one with the company, the other, with a note indicating acceptance of the application, take it for yourself,
to expect the problem to be resolved, management companies are required to consider the complaint no later than 1 month after its acceptance.
to the city administration department if the measures on the filed complaint were not timely considered by the Criminal Code. When contacting the administration, you should write a new application and attach to it a second copy of the complaint previously sent to the Criminal Code.