En-suite sink pipe getting clogged up

[jh2254]

The en-suite sink waste pipe gets clogged up every few years with gunk (tootpaste, soap, etc). This was installed by a professional plumber and he is long gone.
I took apart the U bend, but it was clean. I then smashed a very large tile and found the pipe behind was nearly horizontal going into what looked like the toilet waste system. I took off the pipe and cleaned out the gunk. Problem sorted until next time (a few years).
I then stuck a replacement tile back with velcro!
Is there a better solution than this ? And why did the professional plumber install a near horizontal pipe? Is this normal practice ? Thanks.

 

[ShaunCorbs]

Do you run water when using any products eg tooth paste / soap after ?

 

[jh2254]

Do you run water when using any products eg tooth paste / soap after ?

No not really and I expect this contributed to a quicker build up. We now spit the toothpaste out into the adjacent toilet and it’s slowed the build up , but it still gets clogged up after a couple of years.

 

[ShaunCorbs]

Really need to run some hot water down it afterwards angle / slope looks right should be on the edge of a level line

 

[jh2254]

Really need to run some hot water down it afterwards angle / slope looks right should be on the edge of a level line

Ok thanks. Will keep the Velcro tile just in case I need access in the future !