Range from the cheapest replacement of a toilet float valve £30 (D Boyle Heating based in SM5) to the dearest replacement of a float valve £90 (Yonas Eyeas based in CR4).
Comparing plumbers estimates for replacing a toilet float valve in the cistern tank gives you an idea of who will be better value but the best way to compare costs is to get actual quotes.
What to do - Get rates and quotes to replace a toilet float valve in Carshalton by posting a job with HaMuch and we will send it to plumbers in Carshalton.

"Replace flushing system in toilet cistern"
SM1
"Replace float valve in toilet cistern, water keeps flowing after its flushes"
SM1