
How Expensive Is Water for a Reef Tank or Saltwater Aquarium?
The first step in calculating how much the water is going to cost for your aquarium is to find out how the local water company bills you. There are different ways that municipalities will bill for water. Some charge a flat rate, some are billed by volume or usage, some have pricing tiers. Once you have that information, it's pretty easy to just do the math.
The best way to do this is to find out how much you're paying per gallon of water. If it's a flat rate, well your probably going to pay the same either way. That said, with a tiered system it may benefit you to find out if water for the aquarium will bump you up into the next tier.
How To Add Up Total Gallons Used Annually:
- Calculate how many gallons it takes to fill your aquarium x 1
- Calculate how many gallons you change out with your weekly water changes x 52
- Calculate how many gallons are used to replenish water lost to evaporation each week x 52
- Don't forget to account for the wastewater from your RO/DI system which can vary based on your particular RO/DI system. For every one gallon of product water, your RO/DI system will waste anywhere from 1 - 3 gallons of wastewater.
Once you have these numbers, add them all together to get your annual consumption of water in gallons. Multiply by your charge per gallon for a rough annual cost. Water costs can vary drastically depending on your location. If you have some sort of disposal or water treatment fees that are billed, you will want to add those into your final cost as well.
**Pro-Tip - Purchase an RO/DI system to filter your tap water and produce 0 TDS RO/DI water for your aquarium. It will save you a considerable amount of money compared to buying filtered water at the local fish store. For most hobbyists, it pays for itself within the first 12 months of keeping your aquarium. A water saver RO/DI system that can produce a 1:1 product to wastewater ratio is especially useful in areas where water costs are higher or if you are charged some kind of processing/disposal fee based on usage.
Example for 40-Gallon Aquarium
- 40 gallons
- Water Change of 5 gallons a week x 52 = 260 gallons
- Evaporating 4 gallons a week x 52 = 208 gallons
- RO/DI system with a 1:1 product to wastewater ratio = 580 gallons of wastewater
Add it all up and the total annual consumption of water for a 40-gallon tank is about 1,016 gallons of water. The average cost of water throughout the USA is about $1.50 - $3.00 per 1,000 gallons which means your tank will cost you no more than $3.00 annually for water alone.
Needless to say, the cost of water is typically not a significant ongoing expense. The initial investment in the tank and equipment will be the most costly. The ongoing costs in descending order: Fish food, additives, and filter media (consumables), the cost of energy, and finally water will make up the entirety of your expenses.
Learn More With BRStv: What Is It Going To Cost? Setting Up A Saltwater Tank

Earn 345 Reward Points Earn 690 Reward Points
$69.99
Earn 165 Reward Points Earn 330 Reward Points
$33.99
Earn 270 Reward Points Earn 540 Reward Points
$54.99
Earn 185 Reward Points Earn 370 Reward Points
$37.99
Earn 2,095 Reward Points Earn 4,190 Reward Points
$419.99
Earn 1,920 Reward Points Earn 3,840 Reward Points
$384.99
Earn 1,745 Reward Points Earn 3,490 Reward Points
$349.99
Earn 1,645 Reward Points Earn 3,290 Reward Points
$329.99
Earn 1,845 Reward Points Earn 3,690 Reward Points
$369.99
Earn 1,695 Reward Points Earn 3,390 Reward Points
$339.99
Earn 1,495 Reward Points Earn 2,990 Reward Points
$299.99
Earn 1,395 Reward Points Earn 2,790 Reward Points
$279.99
Earn 1,545 Reward Points Earn 3,090 Reward Points
$309.99
Earn 1,395 Reward Points Earn 2,790 Reward Points
$279.99
Earn 1,145 Reward Points Earn 2,290 Reward Points
$229.99
Earn 1,495 Reward Points Earn 2,990 Reward Points
$299.99
Earn 1,345 Reward Points Earn 2,690 Reward Points
$269.99
Earn 370 Reward Points Earn 740 Reward Points
$74.99
Earn 295 Reward Points Earn 590 Reward Points
$59.99
Earn 140 Reward Points Earn 280 Reward Points
$28.99
Earn 285 Reward Points Earn 570 Reward Points
$57.99
Earn 240 Reward Points Earn 480 Reward Points
$48.99
Earn 160 Reward Points Earn 320 Reward Points
$32.99
Earn 180 Reward Points Earn 360 Reward Points
$36.99
Earn 1,295 Reward Points Earn 2,590 Reward Points
$259.99
Earn 1,445 Reward Points Earn 2,890 Reward Points
$289.99
Earn 250 Reward Points Earn 500 Reward Points
$50.99
Earn 135 Reward Points Earn 270 Reward Points
$27.99
Earn 280 Reward Points Earn 560 Reward Points
$56.99
Earn 205 Reward Points Earn 410 Reward Points
$41.99
Earn 110 Reward Points Earn 220 Reward Points
$22.99
Earn 1,645 Reward Points Earn 3,290 Reward Points
$329.99
Earn 1,395 Reward Points Earn 2,790 Reward Points
$279.99
Earn 1,195 Reward Points Earn 2,390 Reward Points
$239.99
Earn 995 Reward Points Earn 1,990 Reward Points
$199.99
Earn 1,545 Reward Points Earn 3,090 Reward Points
$309.99Categories
BRStv Series
- Aquarium Gear for Beginners
- Beginner's Guide
- BRStv Answers
- BRStv Investigates
- BRStv Problem Solvers
- BRS/WWC Hybrid Method
- Buyer's Guide
- Fish Health
- Master Nutrients: Nitrate, Phosphate and Reef Aquariums
- Neptune Systems Apex Guide
- Product Spotlight & Reviews
- Setup Guide
- Tank Builds
- Tank Profiles & Tours
- Top FAQs
- Top Reefing Mistakes
- Top 10 Tips
- 5 Minute Saltwater Aquarium Guide
Guides & How-Tos
- Additives & Water Chemistry
- Aquarium Controllers
- ATO - Auto Top Off
- Bacteria & Cycling
- BRS Bulk Pharma Additives
- Calcium Reactors
- Coral Propagation & Fragging
- Dosing Pumps
- Filtration & Media
- Fish & Coral Foods
- Heaters & Chillers
- Lighting
- Livestock
- Maintenance
- Plumbing
- Pumps & Water Flow
- Protein Skimmers
- Refugiums
- Reverse Osmosis
- Rock & Sand
- Salt Mix
- Tanks & Sumps
- Test Kits
Charts & Diagrams
Calculators
Problem Solving
Instructions