In the UK, OfWat guarantees that a certain minimum water pressure reaches the boundary of each property in the country. Known as the Guaranteed Standards Scheme (GSS), it should be 9 litres per minute at a pressure of 10m head, or just under 1 bar. Anything more than this should be considered a bonus. It should be noted that this is the pressure received at the boundary, and does not mean that this is the pressure that actually reaches the tap or the shower.
Low water pressure is often a problem if properties are situated at a significant height above the mains, or if the pipework is particularly is narrow and restricted. In these cases, it may be that the water pressure is in the pipes is not sufficient to overcome the static head pressure (the pressure in the pipe). In these cases, it may be that steps need to be taken to boost the water pressure.
Except in particular circumstances, for example where it is used for fire systems, property owners in the UK are not allowed to install an inline pressure pump that draws the water directly from the water mains. Instead, the solution is to install a simple system with a number of features. These features are a small break, or a water storage tank, a suitable air gap, and an overflow that prevents the water flowing back into the water main. Together, these components will allow the water pressure and flow to the property to be increased to an acceptable level.
Successfully boosting the water pressure requires choosing the right equipment. Calculating the right size of pump is dependent on the static head pressure, and the length and diameter of the pipes involved. If the wrong sized pump is installed, it may not be powerful enough or, alternatively, may be producing too much pressure. An additional problem can be that the electrical charge reaching the pump is too high, which can lead to overheating. If water is reaching its destination, and there are no outward signs of problems, it can be difficult to identify that such issues are occurring, but they can all reduce the lifespan of the pump.
When choosing the pump, property owners should consult the manufacturer’s information. This which will include a graph demonstrating the ‘pump curve’. This should be used in conjunction with what known as a ‘system curve’ to show the expected duty point (the expected flow rate and pressure at the point of delivery), to identify the correct size pump and prevent the problems described above.
Another common cause of pump failure is the installation of the wrong type of pump. Pumps may serve one of two functions: delivering high pressure, or delivering high flow rate. Choosing the right type of pump will depend upon the situation. If there is low water pressure but an adequate flow rate, then the high-pressure pump is the right choice. If, however, there is a need to move water quickly, for example to fill a swimming pool or to water crops, then the flow rate is more important.
Dirty water and effluent are the natural byproduct of homes and businesses. High pressure pumps (generally classed as 2 bars and upwards) often struggle to handle such dirty water and effluent. This is due to the high tolerances found in such pumps, which can be easily damaged by the abrasive nature of the fluid and particles. Alternatively, the gritty solution may restrict, and even block, the pipework within the pump. As a result, the pump has to work harder to perform its function, resulting in it running at a higher temperature. If, in addition, the blockages prevent the flow of water around the pump, which would normally keep the pump at an optimal temperature, this will make the overheating worse. Few pump installations are planned with adequate protection against blockages or dry running and, as was discussed above, overworking and overheating can significantly reduce the lifespan of the pump.
One solution to this problem is to install macerator or chopper style pumps. These pumps are designed to break down any solids in the water so that they are small enough to pass through the pump’s free passage without causing damage. These pumps should ideally be utilised where the existing pipes are too small, or too long, and so require higher pressure to push the dirty water to its final destination.
These macerator pumps are often more expensive that the standard type, and they require more maintenance to keep them in good working order. Ensuring that the cutters do not become blocked is key, as failing to do this can cause the pump to become obstructed, and so not function correctly. However, when the correct pump is installed, this can prevent problems from occurring.
It is advised that when installing a macerator pump, a larger bore pipe with a larger free passage forms part of the system. High pressure pumps usually have a larger free passage, enabling them to handle the dirty water more effectively. A high-pressure pump that exceeds the minimum flow speed of the fluid in the pipe (usually 1 metre per second) will help to prevent any solid matter from settling in the bottom of the pipes, so preventing blockages. However, conversely, should the delivery pipe be too large, it may not have enough pressure to move the solids along, leading to obstructions.
While there are a surprising number of private water and wastewater systems in the UK, they are often not properly understood by the people who own and operate them. There are common questions that arise in relation to water and wastewater systems. Some relate to technical issues, such as why previously safe water supplies are suddenly unsanitary, or to legal issues, such as why plumbing back into the mains water system is in breach of the British water regulations. While the answers may be different, the underlying issues are often the same - incorrect installations.
When installing any system that plumbs into the mains, it is necessary to include an air gap between the mains and any system that could possible allow backwash into the mains system. In the event of a valve failure, a break tank with an overflow that allows water to escape at a faster rate than the water flows into it will ensure that there is no backflow. A pump system will allow water to be distributed to where it needs to be. A water storage system is useful where a borehole has a low yield of water so that water supply is uninterrupted, which is also a benefit when repairs are necessary.
As private water systems are almost exclusively in rural, farming areas, where private water supplies fail safety testing, it is usually due to contaminants entering the watercourse. Such contaminants may come from spraying carried out in nearby fields, or from heavy rainfall that caused them to be washed into wells and holding tanks.
In some areas of the UK, there are high natural mineral levels, or a problem known as Greensand. Such minerals can be removed, but will incur a significant cost to do so. While boreholes can be a good investment for those with using less than 20 cubic meters per day are extracted, as no extraction license is needed, it is always advisable to have a full hydro-geological survey completed before any work begins.