As has been said, hot water for sanitary uses (DHW) is distributed through a network parallel and similar to that of cold water, with some differences. In centralized installations (much more economical to operate than individual ones) a storage system is necessary in the technical room (often called boiler room), with a tank in which the volume of water that is statistically calculated to be consumed during one hour, at peak consumption time, is prepared (heated to a temperature of 60 °C or so). If there is preparation by solar heating, there must be another separate tank,[3]​ in which the water preheated with the solar collectors will be stored, and then go to the aforementioned one, where it will be reheated to the distribution temperature, using an auxiliary heating system.

The other difference of the network is that a return pipe is required from the furthest point of the DHW network to the storage tank, with a recirculation pump, to avoid that, if someone opens a distant tap, they have to wait for the water to arrive.[4]​ This pipe will have a recirculation pump or, if the distance is short, the possibility of circulation being done by thermosiphon can be studied.

Furthermore, as it is very convenient that this installation also has a meter (and also mandatory in many countries), the return will start from a point before the meter, preventing recirculation from being done through it, since otherwise, the water that passes through it will be counted and charged at the price of hot water.

Of course, if the building installation has more than one pressure section, the DHW installation will also be divided into the same number of sections and each of the divisions will be like a different installation, with its independent storage tanks, distribution and return pipes.

When it comes to individual centralized preparation systems, the network will run only within the consumption unit (home or premises) and after the heater, whatever type it may be, the parallel hot water network will start. According to Spanish regulations,[5]​ it must have a return pipe when the route from the tank to the furthest point is greater than 15 m.

Copper and plastic pipes are mainly used. They have been used made of lead (prohibited in many countries due to the health problems, lead poisoning, that they can cause), and galvanized steel (called in many places caña, from which comes the name pipes for the entire installation) which, despite being a very suitable material, has stopped being used due to the difficulty of installation and, even more so, of repair, and because they have corrosion problems with hot water.

When it comes to hot water pipes, they must have thermal insulation.

It is very important that the diameters are adequate, because if they are small, apart from the fact that the network will provide insufficient flow rates at peak consumption times, the so-called water hammer can occur, when a faucet or faucet is closed suddenly (which is easy with the current ones that close with a quarter of a turn). The combination of high pressure with high speeds produces a wave in the fluid reaching the tap, which manifests itself in a sharp bang somewhere in the installation (elbow or branch), a real hammer blow, which ends up damaging the pipes when repeated constantly. Apart from preventing adequate diameters (less speed), in ready-made installations, water hammer is solved with slow-closing taps (seat valve) or with strategically placed anti-water hammer devices, which consist of an air cushion that absorbs the pressure of the wave produced.

In many locations, the urban service does not have sufficient flow at certain times of the day, so it is common to have a storage tank in the building, often on the roof and even higher up, using a turret. These elevated tanks (which in some places are called cambijas), are not at all convenient because, heated by the sun, the water in them can reach temperatures above 20 °C, the minimum necessary for the development of legionella. It is more appropriate to place these tanks in the lower part of the buildings, and even better in a basement or cellar, and use a pressure group "Pressure group (plumbing)") to raise it to the floors.

These precautions apply the same in cases where water is obtained from rain and stored in a cistern or when it is extracted from a well using a pump. Its temperature must be prevented by all means from rising above 20 °C, so it must be accumulated in an underground tank and it must not be raised to an elevated tank, but rather the aforementioned pressure group must be used.

Water consumption must be adjusted to the habits of the home's tenants. The following table shows the approximate consumption of each element, for each service use.[6]​ It must be taken into account that these quantities are of mixed water, cold with hot:.

Toilets with two types of discharge are convenient: short (about three liters), for smaller water, and long (five to six liters), for larger water. The problem is that the user often does not clearly understand how each of them is activated when it comes to cisterns with a small button. It is clearer when using large keys (recessed cisterns).

Another saving system is to use the water from the sink to refill the toilet cistern, so that it is cleaned with reused soapy water, like the toilet in the figure.

In public toilets, timed taps should be used, because many users are not careful and do not close when finished.

It is often advised to put an "economizer" on the taps, which consists of a simple device that reduces the flow of water, creating a pressure drop. They can work correctly when the supply is with adequate pressure and flow, but be inconvenient in some cases; for example when a circulating water heater is used[note 6]​ or when the mains water is very hard, because then the salts will deposit and clog the device in a short time.

As has been said, hot water for sanitary uses (DHW) is distributed through a network parallel and similar to that of cold water, with some differences. In centralized installations (much more economical to operate than individual ones) a storage system is necessary in the technical room (often called boiler room), with a tank in which the volume of water that is statistically calculated to be consumed during one hour, at peak consumption time, is prepared (heated to a temperature of 60 °C or so). If there is preparation by solar heating, there must be another separate tank,[3]​ in which the water preheated with the solar collectors will be stored, and then go to the aforementioned one, where it will be reheated to the distribution temperature, using an auxiliary heating system.

The other difference of the network is that a return pipe is required from the furthest point of the DHW network to the storage tank, with a recirculation pump, to avoid that, if someone opens a distant tap, they have to wait for the water to arrive.[4]​ This pipe will have a recirculation pump or, if the distance is short, the possibility of circulation being done by thermosiphon can be studied.

Furthermore, as it is very convenient that this installation also has a meter (and also mandatory in many countries), the return will start from a point before the meter, preventing recirculation from being done through it, since otherwise, the water that passes through it will be counted and charged at the price of hot water.

Of course, if the building installation has more than one pressure section, the DHW installation will also be divided into the same number of sections and each of the divisions will be like a different installation, with its independent storage tanks, distribution and return pipes.

When it comes to individual centralized preparation systems, the network will run only within the consumption unit (home or premises) and after the heater, whatever type it may be, the parallel hot water network will start. According to Spanish regulations,[5]​ it must have a return pipe when the route from the tank to the furthest point is greater than 15 m.

Copper and plastic pipes are mainly used. They have been used made of lead (prohibited in many countries due to the health problems, lead poisoning, that they can cause), and galvanized steel (called in many places caña, from which comes the name pipes for the entire installation) which, despite being a very suitable material, has stopped being used due to the difficulty of installation and, even more so, of repair, and because they have corrosion problems with hot water.

When it comes to hot water pipes, they must have thermal insulation.

It is very important that the diameters are adequate, because if they are small, apart from the fact that the network will provide insufficient flow rates at peak consumption times, the so-called water hammer can occur, when a faucet or faucet is closed suddenly (which is easy with the current ones that close with a quarter of a turn). The combination of high pressure with high speeds produces a wave in the fluid reaching the tap, which manifests itself in a sharp bang somewhere in the installation (elbow or branch), a real hammer blow, which ends up damaging the pipes when repeated constantly. Apart from preventing adequate diameters (less speed), in ready-made installations, water hammer is solved with slow-closing taps (seat valve) or with strategically placed anti-water hammer devices, which consist of an air cushion that absorbs the pressure of the wave produced.

In many locations, the urban service does not have sufficient flow at certain times of the day, so it is common to have a storage tank in the building, often on the roof and even higher up, using a turret. These elevated tanks (which in some places are called cambijas), are not at all convenient because, heated by the sun, the water in them can reach temperatures above 20 °C, the minimum necessary for the development of legionella. It is more appropriate to place these tanks in the lower part of the buildings, and even better in a basement or cellar, and use a pressure group "Pressure group (plumbing)") to raise it to the floors.

These precautions apply the same in cases where water is obtained from rain and stored in a cistern or when it is extracted from a well using a pump. Its temperature must be prevented by all means from rising above 20 °C, so it must be accumulated in an underground tank and it must not be raised to an elevated tank, but rather the aforementioned pressure group must be used.

Water consumption must be adjusted to the habits of the home's tenants. The following table shows the approximate consumption of each element, for each service use.[6]​ It must be taken into account that these quantities are of mixed water, cold with hot:.

Toilets with two types of discharge are convenient: short (about three liters), for smaller water, and long (five to six liters), for larger water. The problem is that the user often does not clearly understand how each of them is activated when it comes to cisterns with a small button. It is clearer when using large keys (recessed cisterns).

Another saving system is to use the water from the sink to refill the toilet cistern, so that it is cleaned with reused soapy water, like the toilet in the figure.

In public toilets, timed taps should be used, because many users are not careful and do not close when finished.

It is often advised to put an "economizer" on the taps, which consists of a simple device that reduces the flow of water, creating a pressure drop. They can work correctly when the supply is with adequate pressure and flow, but be inconvenient in some cases; for example when a circulating water heater is used[note 6]​ or when the mains water is very hard, because then the salts will deposit and clog the device in a short time.