Enter your delivery costs and tank investment to instantly see your break-even month, total savings over 10 years, and whether buying a tank makes financial sense.
Compare your ongoing delivery spend against a one-time tank investment.
Current Water Delivery Costs
Cost Per Delivery
Deliveries / Month
/ mo
Tank Investment
Tank Purchase Price
$
Installation Cost
$
Ongoing Tank Costs (optional)
Monthly Maintenance
$
Annual Price Increase
%
Water After the Tank optional
Cost Per Refill
$
Refills / Month
/ mo
A tank stores water — it doesn't make it. If you will still buy water to fill it (one big tanker load instead of many small deliveries, say), enter that here. Leave blank only if the tank will fill for free, such as from rainwater.
⚠ Please enter your delivery cost per order and deliveries per month, plus the tank purchase price.
WaterTankCalculator.com — Water Delivery vs Tank Cost Results
Your Results
Break-Even Point
—
months
Monthly Delivery Cost
—
Total Tank Investment
—
Annual Delivery Cost
—
5-Year Delivery Cost
—
10-Year Delivery Cost
—
10-Year Net Savings
—
Cumulative Cost Comparison
📖 How To Use
How to Use This Calculator
This tool compares the total cost of continuing water deliveries against buying and owning a storage tank. Here's how to get your personalised break-even result:
Enter your current delivery costs
Input the price you pay per delivery order and how many times per month you receive deliveries. The calculator works out your monthly spend automatically.
Add the tank investment total
Enter the tank purchase price and the installation cost separately. Put the base, fittings, plumbing and labour in the installation field. If you don't have quotes yet, the water tank cost calculator and installation cost estimator give planning figures.
Include ongoing tank costs (optional)
Add any monthly upkeep (cleaning, inspections, spare parts) and the yearly rise you expect in water prices — it uses 3% if you leave it blank. The rise is applied to both your current deliveries and any water you buy to fill the tank.
Enter what it will cost to fill the tank
Most tanks still need water bought in — just in fewer, larger, cheaper-per-litre loads. Enter the cost of each refill and how many you expect a month. This is the step that makes the comparison honest: without it, the calculator assumes the tank's water is free.
Review your results
The calculator shows your break-even month, your monthly saving at today's prices, 10-year savings, and a bar chart comparing what you would have spent on deliveries after 1, 2, 3, 5 and 10 years with the full cost of the tank route — tank, installation, refills and upkeep.
Tip: Use what you actually paid, including minimum-order charges, call-out or emergency premiums and fuel surcharges. Your last few months of receipts are the best guide — averaging them gives a far better break-even than a list price.
📐 The Formula
Water Delivery vs Tank Cost Formula
The calculator adds up two running totals month by month — what you would keep paying for deliveries, and what the tank route costs (tank, installation, refills and upkeep) — and finds the first month the delivery total is higher:
Monthly Delivery Cost = Cost Per Delivery × Deliveries Per Month Monthly Refill Cost = Cost Per Refill × Refills Per Month Total Tank Investment = Purchase Price + Installation Cost Price in Year N = Today's Price × (1 + Annual Increase)N−1 Tank Route to Date = Tank Investment + Σ (Refill Cost + Upkeep) Break-Even Month = first month Σ Delivery Cost ≥ Tank Route to Date 10-Year Savings = 10-yr Delivery Cost − 10-yr Tank Route
Price rises are compounded once a year. If deliveries cost $100 a month today and prices rise 3% a year, you'll be paying about $130 a month in Year 10 (100 × 1.039). Refills rise at the same rate, so a higher inflation figure helps the tank only as much as it cuts what you buy. Upkeep is kept flat. With no price rise, the break-even month is simply the tank investment divided by the monthly saving.
Sample Break-Even Scenarios
Monthly Delivery
Tank Cost
Refills / mo
Price Rise/yr
Break-Even
10-yr Savings
$60
$800
$0 (rainwater)
3%
14 months
$7,454
$100
$1,200
$30
3%
17 months
$8,430
$150
$2,000
$50
5%
20 months
$13,093
$200
$3,500
$80
3%
29 months
$13,008
$300
$6,000
$120
5%
32 months
$21,168
Worked out with this calculator, with no upkeep cost. "Tank cost" is the tank plus installation. Your figures will depend on your own prices, how often you buy water, and local price trends.
💡 When to Use
When Does Buying a Tank Make Sense?
This calculator is designed for anyone currently paying for recurring water deliveries who is weighing the investment in permanent storage.
🏠
Rural & Off-Grid Households
Not connected to mains water. A bigger tank turns many small, expensive deliveries into fewer bulk loads — and can collect rainwater for free in between.
🏗️
Construction Sites
Sites paying for several deliveries a week can often cut costs with on-site storage filled by bulk loads. For a short project, compare hiring a tank with buying one.
🚜
Farms & Agricultural Land
Livestock water, irrigation and seasonal peaks make large-volume storage valuable — a few days of stored water also protects animals when a delivery is late.
🏢
Commercial Properties
Restaurants, laundries and commercial kitchens on unreliable or low-pressure supply use storage to keep running and to buy water in bulk rather than at emergency rates.
Rule of thumb: If a year's saving — what you spend on deliveries now, minus what you'll still spend on refills and upkeep — is more than the tank plus installation, you'll break even within about 12 months. Use the calculator to confirm the exact month.
🧮 Worked Example
Worked example: small deliveries vs a tank and one tanker a month
A household buys six small deliveries a month at $25 each — $150 a month. A 5,000 L tank would let them take one bulk tanker load a month instead, at $70. The tank costs $900, installation $300, and they allow $5 a month for cleaning and upkeep. Prices rise 3% a year.
Break-even: $1,200 ÷ $75 = 16 months — the calculator also shows 16 months, because the first price rise only arrives in month 13.
10 years of deliveries:$20,635. 10 years of the tank route (tank, installation, refills, upkeep): $11,430.
10-year savings: about $9,205.
If the same household had entered no refill cost, the calculator would have shown a break-even of 9 months and 10-year savings of about $18,835 — which is why the refill fields matter. Before buying, check that the tank is big enough to last between loads with the tank size for home calculator.
❓ FAQ
Frequently Asked Questions
How long does it take for a water tank to pay for itself?
It depends on the monthly saving, not just the delivery bill: what you spend on deliveries now, minus what you will still spend filling and looking after the tank. Divide the tank plus installation by that monthly saving for a quick answer. In the worked example on this page, a $1,200 tank that cuts monthly water spending from $150 to $75 (including upkeep) pays for itself in 16 months. The calculator adds yearly price rises for the exact month.
What should I include in the "installation cost" field?
Include every one-time cost beyond the tank itself: plumber labour, pipework, inlet and outlet fittings, overflow, a first-flush diverter if you collect rainwater, base preparation or a concrete pad, a pump if needed, and any permit fees. For a ground-level tank this is often around 20–40% of the tank price, and more for rooftop or underground tanks. The installation cost estimator breaks it down.
What is a realistic annual water delivery price increase to use?
There is no single figure — delivery prices follow local fuel costs, wages and water scarcity, and can jump in a dry season. The best guide is how much your own supplier's price has changed over the last few years. If you don't know, run the calculator at 3% and again at a higher figure such as 6–8% to see how sensitive your break-even is. Because refills rise at the same rate, a higher figure mostly helps when the tank cuts your purchases substantially.
Does this calculator account for the cost of water to fill the tank?
Yes — use the "Water After the Tank" fields. Enter the cost of each refill and how many you expect each month. For example, if you now take four small deliveries a month but would need one bulk tanker load after installing a tank, enter that one load and its price. If the tank will be filled by rainwater or another free source, leave the fields blank. Only leave them blank when that is really true, or the savings will be overstated.
What is the calculator for water delivery vs tank cost?
This is a financial break-even tool that compares two scenarios: (1) continuing to pay for regular water deliveries, and (2) purchasing a storage tank. It works out the month when the money saved on deliveries has paid for the tank — after allowing for refills, upkeep and yearly price rises — and shows delivery spending over 5 and 10 years alongside the 10-year saving.
Is buying a bigger tank better value than a smaller one?
Generally, larger tanks offer better cost-per-litre value and reduce refill frequency, lowering long-term delivery costs further. However, a larger tank has a higher upfront cost, which extends the break-even period. Use the water storage cost per litre calculator alongside this tool to compare tank sizes before deciding.
How do I compare plastic vs steel tank costs for this decision?
Plastic (polyethylene) tanks have lower upfront costs and need little upkeep beyond periodic cleaning, which usually gives the shortest break-even. Steel tanks cost more initially and may have corrosion maintenance costs, but often have longer lifespans. Enter each scenario separately into this calculator and compare. You can also use our plastic vs steel tank cost calculator for a detailed material comparison.
How do I keep delivered water safe in a storage tank?
Buy from a supplier who can show the water's source and uses a clean, dedicated tanker. Keep the tank covered with a tight lid and screened vents and overflow so insects, birds and dust can't get in, keep it out of direct sun where you can, and clean it regularly — many owners do this once or twice a year. Draw water from just above the bottom rather than from the sediment. The WHO Guidelines for Drinking-water Quality treat storage tanks as one of the points where safe water can become contaminated, so if the water is for drinking, treat or test it as your local health authority advises.
✅ Sources & Review
Sources and review
This is a cash-flow calculator: every price comes from you, so the result is only as good as the figures you enter. The method and the advice on this page draw on:
Simple payback and cumulative cash-flow comparison, as used in standard engineering-economics practice: costs are added month by month for each option and the crossover month is reported. No discounting is applied, so treat long paybacks with caution.
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
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