New public health advice

Here’s where you can see what water restrictions apply in your area, and what this means for you.

We get it. It’s been frustrating to be asked to keep an eye on your wai when there’s water being lost through leaks. While we’re not out of the woods yet, significant work has been done on the leaks in the public network – and now they’re close to a sustainable level. This keeps water loss at a minimum, while ensuring repairs are fast and cost-efficient. There’s still work to do. Pipe renewals are key to a long-term reduction in water loss, and leaks will keep on popping up in the aging network, so we’re not taking our eye off the ball. But we all have a role to play. Water restrictions are a simple, effective tool to help people understand how and when we need to manage their water use – in a way that isn't a hassle in day-to-day life! If people follow the restrictions, it reduces the chance of moving to higher levels. Water restrictions are enforced through council bylaws. Wellington Water recommend the level of restrictions for our council owners to implement.

Over summer 2021/22 and 2022/23, there was a real risk of tighter water restrictions – but they’ve been narrowly avoided thanks to substantial and unusual rainfall in summer because of ex-tropical cyclones Dovi and Gabrielle. We can’t assume that this will happen again. This combination of increasing leaks, population growth, above average water use, and dry conditions all increase the risk of tighter water restrictions.

Rain helps us fill the storage lakes during winter, so we can use it during summer when river levels drop. But this storage has a limit – once it’s full, it’s full, and more rain in winter doesn’t change that. We've got to be careful to conserve the water in the storage lakes, and not use too much, too fast. But heavy rain can be just as bad as not enough! We’re only able to take water from the rivers when they’re above a certain water level. When there’s short bursts of heavy rain, it can fill rivers with dirt, sticks and debris. This makes it harder to treat (make safe to drink) and risks blocking the pipe and tunnels that supply the treatment plants. This means that sudden downpours are much less helpful than they seem. Currently, the two storage lakes (the Macaskill Lakes, at Te Mārua) store up to 3.35 billion litres of water – enough to supplement supply for 2 – 3 months in summer. Wellington Water and our council owners are progressing plans to increase the available water storage.

Our modelling showed that in an average summer – meaning no significant rainfall – our councils would have to put tighter water restrictions in place to reduce the risk of an acute water shortage. This comes down to water demand and supply capacity. Water use in the metropolitan Wellington region is at an all-time high. Leaks are increasing due to the water network being old, population growth is driving up the demand for water and Wellingtonian’s simply use more water than comparable regions. We also have a finite amount of water we can treat and supply on any given day. This includes a “buffer” that allows for varying levels in daily water usage, unplanned outages, or planned maintenance work. However, the increase in leaks in the network means the available ‘buffer’ is becoming increasingly tight. In winter, when there is plenty of rain and the river levels are healthy, we can supply up to about 220 million litres of water per day. But in summer, when it’s hot and dry and river levels drop, this can go down to about 170 million litres of water per day. 170 million litres might sound like a lot, but Wellington is using and losing more water than ever before – often getting up to 205 million litres per day in summer! You can see that those numbers don’t work. When demand is higher than the available supply from the rivers and aquifer, then we have to dip into the water stored in the storage lakes. But this stored water is precious and is critical for getting through a long dry period, and in summer it’s harder to refill the lakes. So over time, they get lower and lower, leaving Wellington with less and less water stored and available until next winter.

Wellington’s daily water supply has a limit, as the treatment plants can only supply so much. If demand exceeds what the treatment plants can supply there’s a risk that the water levels in the storage reservoirs across the region are drawn down too low, causing water quality issues and in an extreme scenario even depressurising areas of the network. This can be dangerous as it increases the risk of contamination of drinking water, and boil water notices may need to be issued to stop people getting sick. This means we have to be very careful to manage the daily water supply and demand, and don’t use too much. That’s where water restrictions come in. They help everyone understand how they can best manage their personal water use, so there’s enough to go round for the necessities. Level 1 splits outdoor water use between odd and even houses, to spread the load of daily water demand. This means people can water their gardens regularly without everyone using a lot of water all at once. It also reduces waste by restricting watering to the morning and evening, when water is less likely to evaporate in the heat of the day. Level 2 makes sure people are watering their gardens only when they really need to, with no sprinklers or irrigation systems, and only watering gardens by hand. Level 3 comes into play when we need to take serious action, and all residential outdoor water use must be stopped. We know that people put a lot of hard mahi and love into their gardens, so consider using grey water to water your garden – just not your vegetables, or any plants you’re planning on eating. Level 4 means we’re in a significant water shortage. On top of stopping all outdoor water use, we must reduce indoor use. This could include 2-minute showers and reducing laundry to one load per person, per week.