Stop guessing and start comparing. These free tools help homeowners, farmers, and facility managers calculate the true cost of water storage — from tank purchase and installation to long-term bill savings and material trade-offs.
The Cost & Comparison category brings together eight free calculators designed for anyone who needs to make a financially informed decision about water storage. Whether you're a homeowner trying to cut utility bills, a rural landowner evaluating water supply alternatives, a property developer costing out a new build, or a facilities manager comparing tank replacement options — these tools give you transparent numbers you can check, not a sales figure.
Each calculator in this section goes beyond the sticker price. You'll find tools that calculate total cost of ownership over 10–20 years, compare material durability against upfront savings, and show you the exact year at which an investment pays for itself. The goal is to replace guesswork and sales brochures with transparent, objective calculations you can trust before committing to a purchase.
All tools are free, require no sign-up, and work on any device. Where a calculator supplies its own prices, they are clearly labelled planning estimates and the page explains how they were set — prices differ from town to town, so every tool also lets you enter your own quotes. Each calculator shows its formula and a worked example, lists its sources, and was reviewed by John Mac, PE.
🧭 Guide
How to Choose the Right Cost Calculator
Start with the Water Tank Cost Calculator if you don't yet own a tank and need a ballpark figure for budgeting. It covers the widest range of tank types and sizes, and gives you a realistic price range before you approach suppliers. This is the right starting point for most homeowners and developers.
Use the Plastic vs Steel Calculator when you've narrowed it down to two material choices and want to see which is cheaper in the long run. Steel costs more upfront; stainless steel can last longer than plastic, while unlined galvanised steel may not. This tool compares them on cost per year of use, so a longer life gets proper credit.
Run the Water Bill Savings Calculator if you already have a tank (or plan to install one) and want to quantify the financial benefit. It's especially powerful for households in areas with high water tariffs or those planning to harvest rainwater, where savings can be substantial over time.
Use the Delivery vs Tank and Borehole vs Mains calculators for rural or off-grid properties where the water supply itself is the main cost driver. These are decision-support tools: they model several years of costs side by side — including what you still pay for water, power and upkeep after the switch — so you can see when an alternative really comes out ahead.
Pro tip: Use the Cost Per Litre calculator as a quick benchmark when comparing quotes from multiple suppliers. A lower sticker price doesn't always mean better value — a larger tank at a modestly higher price often gives much cheaper storage per litre, and a longer-lasting tank can be cheaper per year. Compare quotes on the cost per 1,000 L per year.
✅ Sources & Review
How These Calculators Are Built and Reviewed
Prices vary too much from place to place for any website to know your local market, so these calculators either use your own quotes or clearly labelled planning estimates, and every page explains its method with a worked example. The engineering, safety and water-use figures come from published sources, including:
US EPA WaterSense — How We Use Water: household water use and the indoor/outdoor split, used by the bill savings calculator.
NIST SP 811 — unit conversions (litres, US and UK gallons, cubic metres).
Reviewed by John Mac, PE, Water Systems Specialist
Texas-licensed Professional Engineer with 13+ years in residential water storage and 180+ tank projects. John writes and reviews every calculator on this site.
Last updated
❓ FAQ
Frequently Asked Questions
How much does a water tank cost on average?
It depends mostly on size, material and where you live. In the planning data behind our Water Tank Cost Calculator, a 5,000-litre plastic tank costs roughly $400–$1,250 in a mid-range market and about twice that in the US, EU or Australia. Steel and fibreglass tanks cost roughly 2–4 times as much as plastic to buy. Installation typically adds 20–40% for a ground-level tank, and more for rooftop or underground. Enter your supplier's price in the calculator for a figure based on a real quote.
Is plastic or steel cheaper for water storage?
Plastic (polyethylene) tanks are almost always cheaper to buy — in our planning data, roughly half the price of steel per litre or less. Lifespan decides the rest: quality plastic tanks are commonly planned at 15–25 years, unlined galvanised steel at 10–20, lined galvanised at 20–30 and stainless steel at 25–40. A longer-lasting tank can be cheaper per year even if it costs more upfront. The Plastic vs Steel Calculator compares them on cost per year of use with your own prices.
How much can I save on water bills with a storage tank?
Savings depend on how much mains water the tank replaces and what you pay per unit. The arithmetic is simple: 5,000 litres a month is 5 kL, so at a water price of $3 per kL it saves about $15 a month, or $180 a year — more if your sewer charge is also based on metered water and that part falls too, less once pump power and upkeep are taken off. Our Water Bill Savings Calculator works this out from your own bill, including payback period.
Is it cheaper to get water delivered or buy a tank?
A tank doesn't make water, so the question is whether it lets you buy water more cheaply — for example, one large tanker load a month instead of many small deliveries, or rainwater for free. The monthly saving is what you spend on deliveries now, minus what you'll spend filling and maintaining the tank. In the worked example in our Delivery vs Tank Calculator, cutting water spending from $150 to $75 a month pays back a $1,200 tank in 16 months.
What is the cheapest cost per litre for water storage?
Large plastic tanks usually give the lowest purchase cost per litre, and bigger is cheaper per litre: in our planning model, a tank ten times the size costs only about six times as much. Small tanks cost more per litre because fittings, the base and labour are spread over less water. To compare real quotes fairly — including tanks that last different lengths of time — use the cost per 1,000 L per year from the Cost Per Litre Calculator.
Is a rooftop or underground tank more cost-effective?
A rooftop tank is usually cheaper overall: there is no digging, and gravity can supply the house without a pump. But the roof has to carry the full weight — about 1 kg per litre — and gravity pressure is low, about 0.1 bar per metre of height, so many homes add a booster pump. An underground tank always needs a pump and costs more to install, but it saves roof load and space and may last longer out of the sun. In the worked example in our Underground vs Rooftop Calculator, rooftop is $3,950 cheaper over 10 years for a 2,000 L tank.
How do I compare borehole vs mains water costs?
Add up the borehole's upfront cost (drilling, pump, treatment, pipework) and its yearly running costs (servicing, water testing, electricity and an occasional new pump), and compare them year by year with your mains bill. Pumping electricity is usually small — lifting 1 m³ of water through 100 m takes about 0.7 kWh — so servicing and testing matter more. Volume is the key: in the worked example in our Borehole vs Mains Calculator, a home using 1,200 L a day pays back a 12,500 borehole in under 6 years, while at 400 L a day it takes about 19 years.
