It is easy to tell if you have a low pressure hot water cylinder system and not a mains pressure one. In the morning or evening when everyone in the household is using the bathroom facilities, the water pressure will fluctuate and trickle out of the taps at a much slower rate.


The Problem with Low Pressure

Many of the homes in New Zealand were built with low pressure hot water cylinder systems in the past. It was a hangover from the colonial British era of happily accepting unsatisfactory plumbing with a “grin and bear it” stiff upper lip.

Besides the rather unscientific test above, there are two other ways that you can check if this archaic water system is in your home.

  • If it is possible to see a pipe vent sticking out over the gully trap or your roof and
  • Comparing the pressure from your hot tap and the cold tap. If the hot tap has a much weaker flow pressure than the one coming from the cold tap.
  • Get up to your hot water cylinder and physically inspect it. Low pressure cylinders usually don’t have labels, but mains pressure cylinders have labels indicating they are.


The Problem with Low Pressure Systems

Where do we start? A low pressure cylinder in your home leads to slow, poor water flow during bath filling, showering, garden maintenance, and appliance use. If someone activates a tap in another room when a person is in the shower, it will cause that temperature tap in the shower to turn off. The valves require more frequent washer replacements, or else water begins to leak out of the vent. The elements inside the cylinder can corrode which leads to the complete loss of hot water in the house.


Mains Pressure Superiority

The cylinder of a mains pressure system runs at 600 to 1100 kPa and is made of steel. It has no vent pipe, so there will be no water overflow. The water will be delivered to the entire house in an even, strong flow. This pressure equality is not affected by how many demands are made on the system at any time. Say goodbye to sudden loss of cold or hot in the shower or the pressure reducing to a trickle.


There are low pressure system taps that can be fitted to the replace the ones in the house, that will help to slightly alleviate the slow running flow, but the range of styles is very limited. If all that effort and financial outlay is being contemplated, it may be more cost effective to look at replacing it with a mains pressure cylinder.


Mains pressure systems have a wide range of taps for the householder to select. The technology is far more sophisticated, so mains pressure is more efficient at saving energy, heating the water, and cutting expenditure off the household electricity bill.


Upgrading to a mains pressure costs between $1500 to $2500 (Prices in 2017/2018). They cost more than low pressure cylinders because they are made from steel, which lasts a very long time. The household will also need a new set of valves. The installation will take one day.

Any large home, or a household that offers up accommodation such as Air B&B, room-for-rent, and student digs, will benefit from upgrading to a mains pressure water cylinder. When multiple taps are being used at the same time, mains pressure water systems are the only option to make a shower an event to look forward to, and everyone in the home smiling with convenience.