# A Kiwi's Guide to Large Water Storage Tanks for Total Resilience **By Phil East** · 2026-04-03 ![](https://cdn.shopify.com/s/files/1/0671/7603/8633/files/Water_Storage_Tanks_for_Disasters_NZ.png?v=1775209413) When a disaster hits, clean water is the first thing to go. We saw it when the **2016 Kaikōura earthquake** severed infrastructure, isolating communities for weeks. We saw it again when the **2023 Auckland Anniversary floods** and **Cyclone Gabrielle** overwhelmed and contaminated city and regional water supplies. The official advice from Civil Defence is to have enough water for three days, but as we’ve learned the hard way, disruptions can last much, much longer. For genuine peace of mind and resilience, a **large water storage tank** is one of the best investments a Kiwi household, farm, or business can make. It creates a life-sustaining buffer when the taps run dry, moving you from short-term survival to long-term self-sufficiency. ## Securing Your Water Beyond the First 72 Hours The National Emergency Management Agency's (NEMA) [Get Ready NZ](https://getready.govt.nz/) advice is clear: store at least **three litres** of water per person, per day, for a **minimum of three days**. This is the absolute baseline, the foundation of your emergency plan. But New Zealand's history of natural disasters—from earthquakes and floods to volcanic alerts—shows us that 72 hours can disappear in the blink of an eye. Take the **2016 Kaikōura earthquake**. It didn't just disrupt the town for a few days; it cut it off for weeks. Roads were gone, and supply lines were completely severed. A three-day stash of bottled water would have run out long before help could get through, leaving residents to rely on emergency distributions and whatever natural sources they could find and purify. Similarly, after Cyclone Gabrielle, many communities in Hawke's Bay and Tairāwhiti were isolated for extended periods, with damaged pipes and contaminated water sources making stored water a critical lifeline. > **"A major emergency, like a large earthquake or a volcanic eruption, can damage pipes and treatment plants. It can also cut off the water supply to your home. Without a safe and reliable water source, you may be unable to stay in your home." - Get Ready NZ** This is where we need to shift our mindset from short-term survival to long-term **water resilience**. It’s not just about having enough to drink. It's about maintaining health, hygiene, and a sense of normalcy through a prolonged crisis. This includes water for essential tasks like: - **Cooking:** Rehydrating freeze-dried meals, boiling pasta, or washing vegetables. - **Hygiene:** Washing hands, brushing teeth, and basic personal cleaning to prevent illness. - **Sanitation:** Flushing toilets (if possible) or managing emergency waste, which is vital for preventing the spread of disease in a post-disaster environment. Here’s a breakdown of the minimum water you should have on hand, based on NEMA's recommendations, extended for greater resilience. ### Minimum Water Storage Per Person For Emergencies Use Litres Per Day Total for 3 Days (72 Hours) Total for 7 Days **Drinking** **3 litres** **9 litres** **21 litres** **Cooking & Basic Hygiene** **7 litres** **21 litres** **49 litres** **Total Recommended** **10 litres** **30 litres** **70 litres** As you can see, a family of four’s 36-litre, 72-hour supply for drinking alone is quickly overwhelmed by these other essential needs. This is precisely where large water storage tanks prove their worth, providing a significant reserve that gets you past that initial crisis period and into a more sustainable situation. ### Learning from New Zealand's Water Infrastructure Even our biggest cities rely on massive storage systems. Auckland's **1.6 million** residents depend on dams in the Hūnua and Waitākere Ranges to buffer the water supply. The Mangatangi Dam, for example, finished in **1977**, holds a mind-boggling **35.3 gigalitres**—that's enough to fill about **14,000** Olympic-sized swimming pools. These huge-scale systems operate on the exact same principle as a household tank: have a reserve ready for when the main system fails or is overwhelmed, as seen during Auckland's severe drought in 2020. The goal is to build a robust defence against the unexpected. By investing in a large water storage solution, you ensure your household can function safely and comfortably, no matter what’s happening with the municipal supply. It’s a core piece of any serious preparedness strategy, just as vital as the gear in your emergency kit. To see how water storage fits into a complete plan, check out our guide on **[building the ultimate survival gear kit](https://www.next72hours.com/blogs/news/survival-gear-kit)**. ## How to Choose the Right Water Tank for New Zealand Conditions Picking the right water tank is a massive decision for any Kiwi household serious about preparedness. In New Zealand, we’re not just dealing with the basics; our tanks have to stand up to intense UV rays, corrosive coastal salt spray, alpine weather, and the ever-present risk of seismic activity. Getting this choice right means having a reliable water source when you need it most, whether you're in an isolated rural community or a suburb hit by infrastructure failure. Getting it wrong could mean a catastrophic failure just when an emergency hits. This guide will walk you through the key factors, helping you make the best choice for our unique Aotearoa conditions. ### Comparing Water Tank Materials Here in New Zealand, the big three materials for large water tanks are polyethylene (plastic), steel, and concrete. Each has its place, but they come with different trade-offs depending on your budget, where you live, and the specific risks you face. A plastic tank, for instance, is a common sight on lifestyle blocks from Northland to Southland. They’re lightweight and won't rust, which is great for coastal properties in places like the Coromandel or West Coast. But they absolutely must have good UV protection to survive our brutal sun. On the other end of the scale, a concrete tank is incredibly durable and fire-proof, but it's a permanent, expensive installation that needs to be engineered correctly to withstand earthquakes. Here's an honest breakdown of what you're looking at. #### Comparing Water Tank Materials for Kiwi Homes Material Pros Cons Best For **Polyethylene (Plastic)** Lightweight, rust-proof, cost-effective, and easy to install. Opaque tanks resist algae growth. Can be damaged by fire. Cheaper models with poor UV resistance can become brittle over time. General residential use, lifestyle blocks, and coastal properties where rust is a major concern. **Steel (Corrugated/Lined)** Strong and durable with good fire resistance. Available in very large capacities. Can rust if the lining gets damaged or it’s not a stainless steel model. Installation is more complex. Rural and farm applications needing huge volumes, and properties in high fire-risk zones like Canterbury or Marlborough. **Concrete** Extremely durable and long-lasting. Fire-proof and can be installed underground to save space and for aesthetics. Very heavy and expensive, requiring specialist installation. Can crack in earthquakes if not properly engineered. May affect the water’s pH. High-end builds, sites with extreme fire risk, or where an underground tank is the only option. Choosing the right material is the first big hurdle, balancing cost against longevity and the specific risks your property faces. ### Calculating Your Required Tank Size Once you’ve settled on a material, you need to figure out the size. This isn't just about a simple "litres per person" guess; it’s a practical calculation based on your ability to collect rainwater versus how much your household actually uses. To get a realistic idea of the tank capacity you need, you have to look at three things: - **Roof Catchment Area:** The total square metre area of your roof that you'll be collecting water from. - **Local Rainfall:** The average annual rainfall for your specific area. You can find this data from sources like NIWA. - **Water Usage:** Your best estimate of daily water consumption for drinking, cooking, hygiene, and anything else like watering the garden. Let's run through a quick, real-world example. Picture a family of four on a lifestyle block in Hawke's Bay, a region known for its dry summers and recent flood events. - Their roof catchment area is **200 square metres**. - The average annual rainfall in their part of the bay is about **800mm**. - The calculation is simple: 200 m² x 800 mm = **160,000 litres** of potential water collection per year. That quick bit of maths shows they could potentially harvest a massive amount of water. Even with a classic Hawke's Bay dry spell, a **25,000-litre** or **30,000-litre** tank would give them a huge buffer for months, getting them through a drought or an earthquake that cuts the mains supply. This whole thought process is a core part of being prepared, as this simple flowchart shows. ![A flowchart titled 'Emergency Water Decision Guide' showing decisions based on 'Disaster?' and 'Have Tank?'.](https://cdnimg.co/7d85ab33-e9a3-4b26-bd5e-c285b7d50700/9cf6fb31-153c-4eac-aa06-703a6ab9e943/large-water-storage-tanks-water-flowchart.jpg) It really boils down to one question: when a disaster strikes, will you have water? Having a tank puts you on the right side of that equation. For a closer look at the gear needed to make sure that water is safe to drink, you might want to check out our full range of **[water and purification solutions](https://www.next72hours.com/collections/water-and-purification)** built for any emergency scenario. ### Making Your Tank Resilient to NZ’s Hazards Here in New Zealand, we have to plan for the ground moving and the water rising. An unsecured tank is a massive liability in an emergency. - **Seismic Restraints:** If you live in an earthquake-prone area (which is basically all of us), your tank needs to be properly secured. This means using engineered steel brackets or cables to bolt the tank to its concrete pad so it doesn’t slide or topple over when the shaking starts. This was a key lesson from the Christchurch earthquakes. - **Flexible Fittings:** This is a non-negotiable. The pipes connecting your tank to your house must be flexible. Rigid PVC pipes will snap like a twig during an earthquake, and all your stored water will drain away just when you need it most. - **Flood Zone Smarts:** If you’re on a floodplain, like many communities in Hawke's Bay or the West Coast, your tank needs to be raised on a platform. This keeps the tank itself out of contaminated floodwaters and prevents it from floating away. It's well worth your time to [learn how to check if your address is in a flood zone in NZ](https://www.next72hours.com/blogs/news/how-to-check-flood-zone-by-address-nz) before you even think about where to place it. Putting in this effort upfront is what turns a water tank from just a plastic drum into a genuine lifeline for you and your family. ## Plumbing Your Tank for Safe and Reliable Access ![A detailed cross-section of a home rainwater harvesting system with collection, filtering, storage, and pumping.](https://cdnimg.co/7d85ab33-e9a3-4b26-bd5e-c285b7d50700/f5a6a4b5-6f56-4c22-9c33-250649620b64/large-water-storage-tanks-rainwater-harvesting.jpg) Having a full **25,000-litre** tank is a brilliant first step. But all that water is useless if you can’t get to it when the taps run dry or power is out. Correctly plumbing your tank is what turns a big plastic drum into a lifeline for your household’s emergency plan. Getting it right from the start means you’ll have safe, reliable water whether you’re facing a short-term boil water notice after a storm or a prolonged infrastructure failure after an earthquake. The two main ways to get water out are through gravity or a pump, and the right choice depends on your property, budget, and what you need that water for. ### Gravity-Fed Systems: Simplicity and Reliability A gravity-fed system is the definition of bomb-proof. It has no moving parts and needs zero power to work. The whole thing runs on a simple principle: water flows downhill. By setting up your tank on higher ground or a solid raised platform, gravity alone creates enough pressure to run an outdoor tap. It won't be enough to power your shower, but it’s perfect for filling buckets and containers for cooking, drinking, and basic hygiene. Its biggest advantage is its utter reliability during a power cut—a common reality for many Kiwis during events like the Auckland Anniversary floods or nationwide storms. ### Pump Systems for Mains-Like Pressure If you’re looking for a more integrated setup that gives you proper mains-like pressure, you’ll need a pump. A good electric pump can be plumbed directly into your house, letting you use your taps, flush the loo, and even run the hot water cylinder just like normal. This is the gold standard for long-term comfort if the town supply is out for weeks. But there’s a catch: pumps need power. During an outage, which is exactly when you need your tank, a standard pump is just a fancy metal box. That’s why many Kiwis pair their pumps with a generator or a solar power setup with battery storage, creating a truly resilient, off-grid water system. ### The First Line of Defence: First-Flush Diverters Before a single drop even hits your tank, you need to think about keeping it clean. Rainwater that runs off your roof isn’t pure. It’s washing down dust, leaves, bird droppings, and atmospheric pollutants, especially after a long dry spell or if you live near an area with volcanic activity, like the central plateau. A **first-flush diverter** is a simple but critical piece of kit. It automatically redirects the first, most contaminated wash of rainwater away from your tank. This one small addition makes a massive difference to the quality of your stored water, reducing sludge build-up and making the final purification steps much, much easier. > The Ministry of Health strongly advises a multi-barrier approach to ensure rainwater is safe for drinking. This means using several steps to remove or inactivate contaminants, rather than relying on a single method. This “multi-barrier” approach is the key to safe drinking water. It starts with keeping your roof and gutters clean, installing that first-flush diverter, and then filtering and purifying the water before you drink it. Sediment filters are a great starting point for getting rid of physical bits. For a more serious setup that can handle pathogens, a high-performance system like the **[PuriBag Pro Membrane Filter Kit](https://www.next72hours.com/products/puribag-pro-membrane-filter-kit)** can process large volumes of water, making it safe to drink. Finally, you need a failsafe. A final point-of-use purification step gives you total peace of mind. Things like our **Ef-Chlor water purification tablets** provide a guaranteed last line of defence, killing any lingering bacteria or viruses right before you drink the water. This combination of pre-filtering and final purification is the gold standard for turning your big water tank into a safe, long-term drinking water supply. ## Maintaining Your Water Supply for Long-Term Readiness A big water tank is a serious investment in your family's resilience, but it’s absolutely not a "set and forget" solution. It's a lesson we learned the hard way after the **2011 Christchurch earthquakes**, watching municipal water systems fail almost instantly and stay broken for months. Your private system is no different—it needs regular care to be ready when disaster strikes. Consistent maintenance is what guarantees your water supply will be safe and clean when you need it most. Thankfully, it's not a massive chore. It’s just about being proactive and following a simple schedule. ### Your Quarterly Maintenance Checklist Every **three months**, set aside a few minutes to walk around your tank and rainwater collection system. These quick checks are your first line of defence against bigger problems down the track. - **Check Gutters and Roof:** Clear out any leaves, branches, and other junk. This stops organic matter from washing into your tank, where it can rot and degrade your water quality. - **Inspect Screens:** Make sure the insect and mosquito screens on the tank's inlet and overflow pipes are intact and clear. A torn screen is an open invitation for pests to get in and contaminate your water. - **Look for Leaks:** Give the tank, pipes, and fittings a good visual once-over. You're looking for any drips or wet patches. Even a tiny drip can add up to a huge amount of lost water over time. ### The Annual Deep Dive Once a year, it’s time to get a bit more thorough. This is your chance to properly check the internal condition and structural health of your tank. - **Look for Sludge:** Grab a strong torch and safely have a look inside your tank. Check the bottom for any build-up of sludge or sediment. A thin layer is pretty normal, but if it’s thick, it can harbour bacteria and needs cleaning out. - **Inspect Structural Integrity:** Check the tank walls for any signs of cracking, bulging, or UV damage. This is especially important for older poly tanks that have been sitting in the harsh Kiwi sun for years. - **Verify Seismic Restraints:** If you have seismic restraints fitted, check that they are still tight, secure, and free from rust or corrosion. This is a non-negotiable check after any decent shake. ### When and How to Clean Your Tank According to the Ministry of Health, a well-maintained rainwater tank might only need a full clean-out every few years. You’ll know it’s time if you notice a bad taste or smell, see a lot of sediment, or if your water source gets contaminated—for example, by ash from volcanic activity like we see around Ruapehu, or debris after a major storm. When a clean is due, it's often best to call in the professionals. They have the right gear to safely pump out the sludge without having to empty your entire precious water reserve. If you're determined to DIY, you must follow strict safety protocols. Entering a tank is a confined space and can be extremely dangerous. Even with a spotless tank, the final peace of mind comes from having a last line of defence against invisible nasties. This is what the Ministry of Health calls a multi-barrier approach to water safety. As you can read in our **[guide to water purification tablets](https://www.next72hours.com/blogs/news/water-purification-tablets-nz)**, using a product like our **Ef-Chlor tablets** before drinking provides a guaranteed kill-step for bacteria and viruses. It ensures your stored water is always safe, no matter what. ## Common Questions About Big Water Tanks Putting in a large water storage tank is a serious move towards making your family more resilient. And like any big project, you’re bound to have questions. We get asked a lot about the practical side of things, so here are some straight-up answers to the most common queries we hear from Kiwis. ### How Much Does a Large Water Tank Installation Actually Cost in NZ? The final bill is always more than just the sticker price of the tank. To avoid any nasty surprises, you need to think about the entire system from the ground up. The total cost really hinges on the tank's size and material, how much work is needed to prep the site, and how you plumb it into your house. A simple setup with a smaller tank and an outdoor tap is a world away from a fully plumbed-in **30,000-litre** tank on a concrete pad with an electric pump. Here’s a rough idea of the costs you'll need to factor in: - **The Tank Itself:** A **25,000-litre** poly tank, which is a really popular size for lifestyle blocks around New Zealand, will typically run you between **$3,000 and $5,000**. If you're looking at steel or concrete, expect to pay more. - **The Base:** If you're happy to DIY a compacted sand or gravel base, you might only be out a few hundred dollars for materials. But for a professionally poured concrete pad, you’re likely looking at **$1,500 to $3,000** or even more, depending on the size and site access. - **Plumbing and Fittings:** This is everything from the first-flush diverter and pipes to filters and taps. A basic gravity-fed outdoor tap might be a few hundred dollars. A complete setup with a good quality pump tied into your home's plumbing could easily be **$2,000+**. - **Council Consent:** If your tank is big enough to need a building consent, don't forget to budget for the council's application fees. These can add another several hundred dollars to the total. ### Can I Just Drink the Rainwater Straight From the Tank? In short, no. It’s a really bad idea. While the rain that falls from the sky is pure, its journey to your glass is anything but. Think about it: that water washes everything off your roof—bird droppings, dust, bits of leaf litter, and any chemical sprays from nearby farms. All of that ends up in your tank. Both the Ministry of Health and Civil Defence groups like [Get Ready NZ](https://getready.govt.nz/) are very clear on this: you must treat rainwater before you drink it. > "All water from your tank should be treated before drinking, especially after a disaster." - Get Ready NZ This is why a multi-barrier approach is so important. Your first-flush diverter and filters are a great start, but they aren't foolproof. You absolutely need a final purification method to kill any nasty bacteria or viruses that make it through, ensuring your water is actually safe to drink. ### How Do I Make Sure My Water Tank Survives an Earthquake? This is a massive one for us here in New Zealand. A full water tank weighs tonnes, and the violent shaking of a big quake can make it slide, tip over, or even split open—losing all your water right when you need it most. The lessons from the Christchurch and Kaikōura earthquakes were crystal clear: unsecured infrastructure fails. Securing your tank comes down to two things: - **Seismic Restraints:** The tank has to be physically bolted to its foundation. This usually means using engineer-approved steel brackets or strapping to anchor the tank to its concrete pad. This stops it from sliding around and tearing itself apart. - **Flexible Pipe Connections:** This part is non-negotiable. The pipes that connect your tank to your house absolutely must be flexible. Rigid PVC pipes will just snap when the ground starts moving, draining your tank in minutes. Flexible hoses allow for that movement without breaking the connection. Getting these two things right is the difference between having water after a quake and watching it all drain away. ### How Do I Connect a Rainwater Tank to My House? You’ve got a few options here, ranging from dead simple to fully automated. What you choose will come down to your budget and what you want to achieve in an emergency. These are the most common ways to do it: - **Emergency Outdoor Tap:** This is the simplest, most reliable setup you can have. Just a basic, gravity-fed tap at the base of the tank. It needs no power to work and is perfect for filling up water containers for drinking and cooking. - **Manual Changeover Switch:** A plumber can install a valve that lets you manually switch your home's water supply from the mains to your tank. You'll almost always need a pump with this setup to get enough pressure to run your indoor taps and shower. - **Fully Integrated System:** This is the top-tier option. An automatic controller and pump detect when the mains pressure drops (like in a water outage) and seamlessly switches your house over to the tank. This is a slick system, but it needs professional installation and a reliable backup power source like a generator or solar to be truly useful in a disaster. Each of these options gets you one step closer to true water independence, giving you the confidence that you can look after your family, no matter what happens. * * * At **Next72Hours**, we’re focused on helping New Zealanders get properly prepared for any emergency. Our range of tried-and-tested products, from water purification to emergency food, is all about giving you peace of mind. You can see our full range of preparedness solutions at [https://www.next72hours.com](https://www.next72hours.com). --- > Source: [Next72Hours](https://www.next72hours.com/blogs/news/large-water-storage-tanks)