It is worth checking the outlet holes under the rim and the ridge under the
rim using a small mirror for signs of anything that is obstructing or
disrupting the water flow. If you are in a hard water area you might find
limescale. You can try reducing the volume and therefore the pressure of
water that falls when you flush; a brick in the cistern will reduce the
volume by about a litre, and if you have a hollow plastic ball float on a
metal arm you can bend the arm/float down to further reduce the amount of
water that fills the cistern to make the water inlet valve shut off sooner.
If none of that works that leaves a plastic 'collar' that fits around the
rim to deflect the water downwards. These aren't available to buy, I made
one from some flexible plastic sheet material about 2mm/one eighth of an
HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.