Low pressure hot water is gravity-fed from a header tank above the cylinder, delivering lower water pressure. Mains pressure hot water connects directly to your water supply at full pressure, delivering stronger flow at all outlets. Most Christchurch homes built before 1990 still have low-pressure systems.
| Feature | Low Pressure | Mains Pressure |
|---|---|---|
| Water source | Header tank (ceiling/roof) | Direct from mains supply |
| Pressure | Low (20–80 kPa) | Full (200–600 kPa) |
| Shower feel | Weak flow | Strong flow |
| Multiple outlets | Pressure drops significantly | Maintains good pressure |
| Installation cost | Lower | Higher by $1,000–$1,900 |
Look in your ceiling space or roof space for a cold water storage tank (usually a rectangular plastic tank, 200–400L). If it's there, you're on low pressure. If you have a mains pressure cylinder, there will be no header tank. You can also check the sticker on your cylinder — it will state 'LP' or 'mains pressure.'
Yes, in most cases. If you're already paying for labour to remove and replace a cylinder, adding the mains pressure upgrade is the most cost-effective time to do it. You'll notice an immediate improvement in shower pressure and hot water flow throughout the home.