Plumbing systems in buildings must perform two critical functions. They must ensure a continuous supply of water for all occupants and equipment that requires it. At the same time, they must effectively remove wastewater to avoid health risks. For a healthy building interior, a well-designed plumbing system is required.

Engineers analyze the water requirements of the building when designing a plumbing system to specify the appropriate capacity installation. Water cannot be delivered at the required pressure and flowrate through piping and fixtures that are too small. Oversized plumbing systems, on the other hand, are more expensive and provide no benefits.

Plumbing engineers strongly advise water conservation measures. These measures not only reduce water bills, but also the associated pumping and heating costs. New construction and major renovations are excellent opportunities to save water because designing an efficient drainage system from the start is easier than changing an existing installation.

The plumbing design in buildings that use natural gas for room heating and hot water includes gas piping and connections. Because natural gas is a highly flammable substance, a secure installation is essential.

The specific requirements vary by jurisdiction, but in most cases, a plumbing design must be submitted by a licensed design professional. Only a licensed plumbing contractor can install the project once it has been approved.

Plumbing engineers must first determine the building’s water demand before beginning the design process. The technical specifications and layout of plumbing fixtures, as well as piping diameters, will be determined by this. Water demand must also be known in order to size the hot water system and determine whether or not the local supply is adequate. When the local supply pressure is insufficient for building, a water booster pump is required.

Plumbing fixtures such as showerheads, WCs, and faucets are not the only components in buildings that use water. Automatic sprinklers, for example, rely on water supply as well, and these systems must be considered when calculating the building’s demand. HVAC systems with cooling towers consume water as well, because the towers are constantly evaporating.

When a plumbing system is properly designed, you will always have enough flow and pressure at the farthest fixture, even during times of high water consumption. When demand is high, a faulty plumbing installation cannot deliver enough water to the upper floors. This is a common problem in older high-rise buildings.

Pipe diameter selection is an important step in plumbing system design. Smaller pipes and fittings are less expensive, but an undersized pipe will restrict flow. Oversized pipes, on the other hand, are not recommended because they are more expensive, their fittings are more expensive, and the plumbing installation takes up more space than necessary.

Piping must be sized to ensure that all plumbing fixtures in the building receive sufficient pressure and flow. The calculations are complicated, especially in larger facilities with multiple branches. Plumbing engineers, on the other hand, can use modern design software to determine the pipe sizes that provide a reliable water supply at the lowest possible installation cost.

When trying to calculate pipe sizes for a building, plumbing engineers take the following factors into account:

• Individual fixture, equipment, and appliance water demand
• Elevations and piping lengths
• Pipes, fittings, and other plumbing elements cause hydraulic losses.

Because piping sizes influence pressure and flow, the computation is iterative. Manual procedures take a long time, which was previously a limitation of plumbing design. Modern design software, on the other hand, can significantly accelerate the process. There are simplified pipe computation that use tables and rules, but they frequently result in oversized pipes, increasing the cost of installation.

The native water supply is frequently too cold for building occupants to use. As a result, water heaters are essential in plumbing installations. There are numerous types, each with advantages and disadvantages. Hot water systems are classified according to their energy source and water delivery method:

• Water heating can be accomplished through combustion, which uses fuels such as natural gas or propane, or through electricity. Although combustion heating is typically less expensive than resistance heating, electrical heating pumps can start competing with fuel-based heating.
• Storage heaters have a hot water tank, whereas tankless heaters heat up quickly as water passes through them. Because storage heating systems have standby losses when holding hot water, tankless heaters typically have a higher efficiency.

Combustion heaters should be properly perforated to remove flue gases, but electric heaters do not have this problem. However, the operating costs of a resistance heater can be very strong, especially in places where electricity is expensive. A heat pump water heater is suggested if you are making plans a building that will not use any fossil fuels locally.

The plumbing design must avoid the accumulation of stagnated warm water regardless of the kind of water heater used. This condition fosters the growth of Legionella bacteria, which causes severe respiratory illness. Cooling towers and dead legs in piping are two common places for Legionella to grow.

Hot water must first travel from the water heater to the point of use when it is required in a specific fixture. However, there are some applications, such as hotel rooms, where hot water is required immediately. In this case, there are two options:

• A dedicated tankless heater can be installed in a plumbing fixture that requires immediate hot water. When only one or a few fixtures require instant hot water, this is an effective solution; however, when many fixtures require it, it becomes prohibitively expensive.
• Installing a recirculation loop for all fixtures that require immediate hot water is another option. Instead of many smaller units, a single water heater can be connected to the loop.

An energy factor, which is a ratio of heating output to energy input, describes the energy efficiency of water heaters. Because they use an inverse refrigeration cycle to capture ambient heat, only heat pumps can achieve an energy factor greater than one. The heat input in all other hot water systems is directly from the energy source.

The operating cost of a water heater is determined by both the energy factor and the heat source. Electric resistance heaters have an EF of nearly 1.0, whereas gas heaters typically have an EF of less than 0.8. However, resistance heaters are more expensive to operate because one kilowatt-hour of electricity costs much more than the equivalent 3,412 BTU of natural gas.

Water plays an important role in fire protection, and a consistent water supply is essential when a fire breaks out. Automatic sprinklers are highly effective for fire protection because they can extinguish the majority of fires while they are still small. A sprinkler system, on the other hand, is only reliable if the water supply is guaranteed whenever a fire occurs. Additionally, the piping that provides water to sprinkler heads should meet the manufacturer’s pressure and flow specifications.

All fire protection systems which use standpipes, that are used by firefighters to connect hoses on the inside of a building, also require plumbing design. In other words, a standpipe is comparable to a street fire hydrant but is designed for indoor use.

Pumps may be required in fire protection systems to achieve the required flow and pressure. In fire protection, there are two types of pumps:

• Sprinkler booster pumps, as the name implies, are used to provide an adequate water supply to sprinkler heads.
• Fire pumps are typically larger in size and are used to ensure adequate flow and supply for standpipe systems.

Plumbing engineering is critical in fire protection, particularly when sprinklers and standpipes are involved. Typically, building departments require these systems to be installed by a licensed plumbing or fire suppression contractor.

Plumbing systems in large projects have a complex layout of pipes and fixtures. Many plumbing elements are bulky and heavy, and once in place, the installation cannot be easily modified. As a result, avoiding clashes and specification errors is critical in plumbing design.

Building Information Modeling (BIM) can be used to simplify MEP design, which includes building system coordination. Modern BIM software can detect conflicts between plumbing and other installations and notify the design team so that the problems can be resolved. This helps to avoid change orders during construction, allowing installations to be completed on time and within budget.