Water tank problems

2 problems have recently started with my hot water tank.
1. Every time we have a bath and the tank fills up it starts to drip from the overflow. Running the hot tap for a minute or 2 causes it to stop. 2. At the same time this started I also noticed that I dont get as much hot water into the bath until it starts to run cold.
I seem to remember one time someone told me your tank can start to fill with dirt in the bottom of it. Is this the problem and is it a case of removing the element and scooping out the dirt on the base of the tank. Its awkward because its up high on the wall of the bathroom but I replaced the element about 10-15 years ago so I can do it ok!
Or is the water running cold too soon simply a case of a new element reqd? I always thought they just stopped dead and dont remember the water getting gradually colder in this manner.
Any help or ideas appreciated!
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
Add image file

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.