Possible blocked toilet?

[craigpigott]

A customer called me out to a job saying after she flushes her toilet over the space of a day the toilet water slowly starts to turn brown any help?

 

[craigpigott]

Also this is in the upstairs toilet and the downstairs one doesn't do the same its fine

 

[CT18]

Check the tank something like the flapper may be breaking down or rusting

 

[craigpigott]

It's all plastic the house is only 10 years old