If your Kohler toilet keeps running, fills too slowly, or the water level seems off, chances are the fill valve needs adjusting. The fill valve controls how much water enters the tank after each flush, and setting it correctly ensures strong flushes without wasting water.
In this guide, you’ll learn exactly how to adjust the fill valve on a Kohler toilet, when to replace instead of adjust, and the best Fluidmaster and Kohler fill valves for long-lasting performance.
Quick Picks: Best Fill Valves for Kohler Toilets
- Best Overall: Fluidmaster 400AH PerforMAX High-Performance Fill Valve – Quiet, adjustable, and works with Kohler toilets.
- Best OEM Replacement: Kohler Genuine Part Fill Valve Kit – Perfect factory fit for Kohler models.
- Best Premium Kit: Fluidmaster 400CRP14 Fill Valve & Flapper Repair Kit – Ideal for older Kohler toilets needing a full refresh.
Why Adjust the Fill Valve?
Your Kohler toilet fill valve may need adjusting if you notice:
- Running toilet: Water flows constantly into the bowl.
- Low water level: Weak flushes that don’t clear the bowl properly.
- Too much water: Water overflowing into the tank’s overflow tube.
- Noisy refills: A loud hiss or rush of water after flushing.
Step-by-Step: How to Adjust a Kohler Toilet Fill Valve
Most Kohler toilets use either a Fluidmaster-style float cup fill valve or Kohler’s own OEM version. Both are easy to adjust.
- Turn off the water supply at the wall and remove the tank lid.
- Check your fill valve type: Kohler often uses a vertical float cup design similar to Fluidmaster.
- Locate the adjustment rod or screw: On most models, a long adjustment rod with a clip or a Phillips screw controls the float height.
- Adjust the float:
- To raise the water level, slide the float cup up or turn the screw clockwise.
- To lower the water level, slide the float down or turn the screw counterclockwise.
- Set the water line: Aim for the water to stop about 1 inch below the top of the overflow tube (many Kohler tanks have a mark inside for reference).
- Turn water supply back on and flush to test. Adjust again if needed.
When to Replace Instead of Adjust
If adjusting doesn’t solve the problem, your fill valve may be worn out. Signs you need a replacement include:
- Fill valve keeps sticking after flushing
- Water never fully shuts off
- Leaking from the bottom of the tank
- Valve makes loud or irregular noises
Detailed Product Reviews: Best Fill Valve Replacements for Kohler
1. Fluidmaster 400AH PerforMAX High-Performance Fill Valve
Who it’s for: Kohler owners who want a reliable universal upgrade.
- Key Benefits: Adjustable height, water-saving, quiet performance.
- Pros: Fits nearly all Kohler models, easy to install, dependable shut-off.
- Cons: Slightly pricier than the basic 400A.
Final Verdict: Best all-around replacement for performance and durability.
Check Latest Price
2. Kohler Genuine Part Fill Valve Kit
Who it’s for: Homeowners who want an exact factory match for their Kohler toilet.
- Key Benefits: OEM fit, reliable shut-off, long-term durability.
- Pros: Designed specifically for Kohler models, perfect fit.
- Cons: More expensive than universal models.
Final Verdict: The safest bet if you want OEM reliability.
Check Latest Price
3. Fluidmaster 400CRP14 Fill Valve & Flapper Kit
Who it’s for: Kohler toilets that are older and need multiple parts replaced.
- Key Benefits: Includes fill valve + flapper, fixes running toilets.
- Pros: Complete solution, great value, widely compatible.
- Cons: More parts to install than a single valve.
Final Verdict: Perfect for full repairs, especially if your flapper is also leaking.
Check Latest Price
4. Fluidmaster PRO45 Quiet Fill Valve
Who it’s for: Those who want a professional-grade, quieter option.
- Key Benefits: Quieter refill, heavy-duty design, reliable shut-off.
- Pros: Long-lasting, ultra-quiet, reduces refill noise.
- Cons: Higher price than basic models.
Final Verdict: Best upgrade for quiet operation in bathrooms near bedrooms.
Check Latest Price
5. Fluidmaster 400H-002 Performax Universal Fill Valve
Who it’s for: Homeowners wanting fine-tuned control of water usage.
- Key Benefits: Adjustable water flow and refill speed.
- Pros: Eco-friendly, customizable, universal fit.
- Cons: More setup time required.
Final Verdict: Ideal for saving water while keeping powerful flushes.
Check Latest Price
6. Fluidmaster 402CARHRKP10 Complete Toilet Repair Kit
Who it’s for: Kohler toilets needing a full rebuild of all tank parts.
- Key Benefits: Includes fill valve, flapper, and tank gasket.
- Pros: One kit repairs everything, reliable, long-term fix.
- Cons: More work to install than just a valve.
Final Verdict: Best option if your Kohler toilet is older and multiple parts are worn out.
Check Latest Price
Comparison Table
| Name | Best For | Key Features | Price Link |
|---|---|---|---|
| Fluidmaster 400AH | Universal replacement | Adjustable, quiet, water-saving | View Price |
| Kohler OEM Kit | Exact factory fit | Genuine Kohler replacement | View Price |
| Fluidmaster 400CRP14 | Valve + flapper repair | Complete kit, stops leaks | View Price |
| Fluidmaster PRO45 | Quiet upgrade | Professional-grade, noise-reducing | View Price |
| Fluidmaster 400H-002 | Water efficiency | Adjustable flow + refill | View Price |
| Fluidmaster 402CARHRKP10 | Full rebuild | Complete repair kit | View Price |
FAQ Section
How do I know if my Kohler fill valve needs adjusting?
If your toilet is running constantly, not flushing strongly, or overflowing into the tube, it likely needs adjustment.
Where should the water level be set in a Kohler toilet?
Water should stop about 1 inch below the top of the overflow tube or at the mark inside the tank.
Can I use a Fluidmaster valve in a Kohler toilet?
Yes. Fluidmaster valves are universal and widely used in Kohler toilets.
How long do Kohler fill valves last?
On average 5–7 years, depending on water quality and usage.
When should I replace instead of adjust?
If the valve won’t shut off, leaks from the bottom, or sticks repeatedly, it’s best to replace it.
Conclusion
Learning how to adjust the fill valve on a Kohler toilet can save you from water waste and weak flushes. Simply adjust the float height so water shuts off just below the overflow tube. If that doesn’t solve the problem, your valve may be worn out.
The Fluidmaster 400AH is the best universal replacement, the Kohler OEM kit ensures an exact fit, and the 400CRP14 kit is ideal for full repairs. Adjust or replace today and enjoy a smooth, efficient Kohler flush again.
Get your Kohler-compatible fill valve now and restore proper performance to your toilet.