5 Different Ways To Make Your Toilet Use Less Water

In addition to flushing one tank of water, my experiment showed another 3 liters of water flowed to the overflow tube. I was very surprised to discover this. I will provide a zero cost fix to this problem. I will provide 5 different ways to save on water used in toilet flushing. These techniques are based on the amount of water the toilet tank releases, assuming the toilet bowl is efficient. Watch this video to see the efficient toilet siphon effect: https://youtu.be/_EP7LZdnMXo Note that if your toilet bowl is not efficient, reducing the water flushed may not clear the solid waste well, you may have to flush twice. So one of the best techniques is to have a dual flush system which uses more water for the solid waste than the liquid waste. See the explanation and installation of the dual flush system: https://youtu.be/1RDGznJm-U8

Each of these five water-saving methods works independently, and you can combine several of them on the same toilet for maximum effect. The techniques range from free adjustments to inexpensive part swaps.

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Alternative Methods

Toilet modification for water savings has several approaches.

1. Adjustable Flapper Valve

When to use: Fine-tuning flush volume on a standard toilet without replacing the fill valve.

Pros: Inexpensive, adjustable dial controls water per flush, universal fit for most toilets
Cons: Adjustment can be finicky, rubber degrades over time, may not seal well on older flush valves
Difficulty: Easy
Estimated cost: ~$5-10

2. Toilet Tank Bank or Fill-Cycle Diverter

When to use: Reducing water use without modifying any components.

Pros: Simply displaces water in the tank (tank bank) or diverts excess fill water (diverter), no tools needed
Cons: Minimal savings (0.5-0.8 gallons per flush), does not change flush mechanics
Difficulty: Easy
Estimated cost: ~$2-5

3. Replace with a WaterSense-Certified Toilet

When to use: When the toilet is old (3.5-7 gallons per flush) and modifications are insufficient.

Pros: Uses 1.28 gallons or less per flush, better bowl wash, may qualify for utility rebates
Cons: Full toilet replacement cost and labor, old toilet disposal
Difficulty: Medium to Hard
Estimated cost: ~$100-400 for the toilet plus installation

Tips for Reducing Toilet Water Usage

Saving water sounds simple, but most homeowners make the same few mistakes that either waste the savings or cause flush performance problems. These tips help you get real results.

Measure your current flush volume before making changes. Turn off the water supply, mark the tank water line with a pencil, flush, then measure how much water it takes to refill to that line using a gallon jug. Many people assume their toilet uses 1.6 gallons per flush, but older models use 3.5 to 7 gallons — the savings potential is much bigger than they realize.
Check for phantom flushes and silent leaks first. Before optimizing flush volume, make sure you are not wasting water between flushes. Drop a few drops of food coloring into the tank (not the bowl). Wait 15 minutes without flushing. If color appears in the bowl, your flapper is leaking and every drop of saved water per flush is being offset by continuous leaking.
Do not put bricks in the tank. This old advice is still circulating, but bricks degrade in water, releasing sediment that damages the flapper and fill valve. Bricks can also shift and block the flapper from closing. If you want to displace water, use a sealed plastic bottle filled with water and a handful of pebbles for weight.
Adjust the float level carefully. Lowering the float reduces the water level in the tank, which reduces water per flush. However, lowering it too much weakens the flush and leaves waste behind, leading to double-flushing that uses more water than a single full flush. Lower the float by 1/2 inch at a time and test.
Fix the overflow tube problem. If water continuously trickles into the overflow tube after the tank is full, the fill valve is not shutting off properly. This wastes thousands of gallons per year — far more than anything you save by adjusting flush volume. Replace the fill valve (about $8-12) or adjust the existing one so the water level sits 1 inch below the top of the overflow tube.
Consider a dual flush conversion for the best balance. A dual flush system lets you use a light flush (0.8-1.0 gallons) for liquid waste and a full flush (1.6 gallons) for solid waste. Since most flushes are for liquid, the average per-flush consumption drops dramatically. Our zero-cost dual flush conversion guide shows how to simulate this without buying a kit.
Test flush performance after every adjustment. After each modification, flush several times with and without waste material. A flush that saves water but does not clear the bowl is not a solution — it just means you flush twice.

Tools and Materials

Tool / Material	Purpose	Notes
Gallon jug or measuring container	Measure current flush volume	Fill jug from the tank to measure precisely
Food coloring	Detect silent flapper leaks	A few drops in the tank; check the bowl after 15 minutes
Adjustable pliers or wrench	Adjust fill valve float	Channel-lock pliers work best
Flathead or Phillips screwdriver	Adjust float screw on fill valve	Match the screw head on your specific fill valve
Replacement flapper	Fix leaking flush valve seal	Bring the old flapper to the hardware store to match size
Sealed plastic bottle with pebbles	Displace tank water (alternative to brick)	Use a 1-liter bottle; do not use glass
Pencil	Mark water level lines in tank	Helps track adjustments accurately
Replacement fill valve	Fix overflow tube waste	Universal fill valves ($8-12) fit most toilets
Dual flush conversion kit (optional)	Add dual flush capability	Fluidmaster DuoFlush or Danco HydroRight

When to Call a Professional

Most toilet water-saving modifications are simple DIY tasks, but certain situations benefit from professional help.

Toilet runs constantly and adjustments do not fix it. If replacing the flapper and adjusting the fill valve do not stop the running, the flush valve seat itself may be corroded or warped. A plumber can resurface the seat or replace the entire flush valve.
Very old toilets (pre-1994, 3.5+ gallons per flush). Modifications to a 30-year-old toilet can only do so much. At a certain point, replacing the toilet with a modern WaterSense-certified model saves more water and money over its lifetime than any modification. A plumber can remove the old unit and install the new one in about an hour, including wax ring, supply line, and caulking.
Visible cracks in the tank or bowl. A cracked toilet cannot be reliably sealed and is a flooding risk. Do not attempt modifications on cracked porcelain — replace the entire toilet.
Home on a septic system. If your home uses a septic system, drastically reducing flush water can cause solids to accumulate in the drain line (not enough water to carry them to the tank). A plumber familiar with septic systems can recommend the right flush volume for your setup.

For the zero-cost dual flush conversion method, see our dual flush conversion guide. To reduce bathroom water use even further, our free portable bidet guide cuts toilet paper consumption. For a permanent bidet option, see our bidet seat installation guide. More plumbing tutorials are available on Genius Asian.

Always verify contractor licensing and insurance in your state. Cost estimates are averages and may vary by location.