The flush valve tells a different story. If water is draining slowly from the cistern into the pan even when nobody has touched the button or handle, the flush valve seal or siphon washer has likely perished and is no longer sealing the outlet at the base of the tank. This shows up as a cistern that refills every few minutes with no obvious trigger, sometimes described by customers as topping itself up rather than running continuously. On older gravity-fed systems built around a siphon rather than a valve, a split diaphragm inside the siphon body produces the same symptom.
Noise is a real factor when deciding between the two. A side-entry valve introducing water above the surface tends to produce more splash and a higher-pitched fill sound, which shows up as a complaint on quieter properties such as flats with shared walls. Bottom-entry valves that fill below the surface are noticeably quieter, and Plumb2U Epsom swapping a noisy side-entry unit for a bottom-entry equivalent is a common upgrade even where nothing has technically failed.
The first check is timing. A whistling or high-pitched noise that happens throughout the entire fill cycle, easing off only as the cistern nears full, usually points to wear inside the fill valve itself, most often a perished washer or a worn diaphragm that is no longer sealing smoothly against the valve seat. Water forced through a narrowed or roughened opening produces exactly this kind of noise, and it tends to get worse over time rather than appearing suddenly.
Top-fix hinges solve exactly that access problem by using a bolt and a quick-release or turn-to-tighten fixing that can be adjusted entirely from above the pan, with no need to get underneath at all. This has made top-fix the standard choice on most new soft-close seats sold in the last several years, and it is usually the easier option to specify when the underside of the pan is difficult to reach or when the original fixing has seized.
A cistern that never quite stops filling is one of the most common callouts a plumber gets, and the fix hinges on correctly identifying which of two components has failed: the fill valve or the flush valve. Get this wrong and you swap a part that was never the problem, then head back out a second time.
A bottom-entry fill valve, by contrast, takes its supply vertically through the base of the cistern, in line with where a rising main or supply pipe comes straight up from the floor void or from beneath a low-level suite. This arrangement is generally quieter, since the incoming water enters below the surface of the tank rather than splashing in from the side, which is why many modern and replacement fill valves are built as bottom-entry as standard, often with a side-entry option built into the same body.
Noise is a real factor when deciding between the two. A side-entry valve introducing water above the surface tends to produce more splash and a higher-pitched fill sound, which shows up as a complaint on quieter properties such as flats with shared walls. Bottom-entry valves that fill below the surface are noticeably quieter, and Plumb2U Epsom swapping a noisy side-entry unit for a bottom-entry equivalent is a common upgrade even where nothing has technically failed.
The first check is timing. A whistling or high-pitched noise that happens throughout the entire fill cycle, easing off only as the cistern nears full, usually points to wear inside the fill valve itself, most often a perished washer or a worn diaphragm that is no longer sealing smoothly against the valve seat. Water forced through a narrowed or roughened opening produces exactly this kind of noise, and it tends to get worse over time rather than appearing suddenly.
Top-fix hinges solve exactly that access problem by using a bolt and a quick-release or turn-to-tighten fixing that can be adjusted entirely from above the pan, with no need to get underneath at all. This has made top-fix the standard choice on most new soft-close seats sold in the last several years, and it is usually the easier option to specify when the underside of the pan is difficult to reach or when the original fixing has seized.
A cistern that never quite stops filling is one of the most common callouts a plumber gets, and the fix hinges on correctly identifying which of two components has failed: the fill valve or the flush valve. Get this wrong and you swap a part that was never the problem, then head back out a second time.
A bottom-entry fill valve, by contrast, takes its supply vertically through the base of the cistern, in line with where a rising main or supply pipe comes straight up from the floor void or from beneath a low-level suite. This arrangement is generally quieter, since the incoming water enters below the surface of the tank rather than splashing in from the side, which is why many modern and replacement fill valves are built as bottom-entry as standard, often with a side-entry option built into the same body.
