# Excess network pressure in HSY’s water supply network

The dataset presents the excess network pressure (m) in HSY’s water supply network, i.e. the difference between the actual pressure and the pressure required by the property, on a property-specific basis.

The higher the value, the more the network pressure exceeds the pressure required by the property. If the value is negative, the network pressure may not be sufficient to meet the needs of the property. Excess network pressure at the property increases the flow rate from taps and thus water consumption, and can increase the noise from the network.

If the property has a lot of excess network pressure, the pressure at the property can be reduced with a constant pressure valve. On the other hand, if the network pressure is insufficient, the pressure can be increased using a property-specific pressure booster, i.e. a pump.

The dataset is a combination of several sources. The network pressure for each property has been obtained from the hydraulic model of HSY’s water supply network. If the network pressure varies at different times of the day, the lowest pressure that normally occurs has been used to calculate the excess pressure.

The required pressure per property, in turn, has been calculated using information on the roof height (elevation above sea level) of the tallest building located on the property and the ground elevation. A formula from the manual RIL 237-2-2010 on the design of water networks was used to calculate the pressure level required at the property. The pressure level requirement was calculated as the sum of the elevation of the property’s highest water access point and the pressure loss of the property’s plumbing equipment:

pressure level requirement H = Hg + b

in which

• Hg is the elevation of the property’s highest water access point, Hg = roof height (metres above sea level) – 1 m
• b is the pressure loss of the building’s plumbing equipment, calculated as follows: b = 15 + 0.5*n = pressure loss of fixtures 5 m + lot water pipe 1 m + water meter 4 m + internal piping in a single-storey building 5 m + 0.5 m for each additional floor. The floor height was assumed to be 3 m.
• These provide the result H = (roof height above sea level – 1) + 15 + 0.5*(building height/3)

In the data, the excess pressure is presented as metres of water sprout and classified into ten-metre categories. Ten metres is approximately one bar of pressure.

There may be errors in the data. Therefore, information on the excess network pressure of an individual property should be regarded as indicative. If there is substantial excess pressure according to the data, it is a good idea to confirm this with measurements prior to valve installation.

Classification:

• less than 0 m: There is no excess network pressure or the network pressure is insufficient for the needs of the property.
• 0–10 m: Less than 10 metres of excess network pressure. The network pressure is suitable for the needs of the property.
• 10–20 m: Ten to twenty metres of excess network pressure.
• 20–30 m: 20 to 30 metres of excess network pressure.
• more than 30 m: More than 30 metres of excess network pressure.