toilet drain system. Drainage and wastage systems and plumbing help, advice and answers

[david somerville]

I'VE BUILT AN EXTENTION ONTO MY HOUSE AND NOW INSTALLING A TOILET DOWNSTAIRS. NOT SURE WHAT THE SLOPE OF THE DRAIN PIPE GOING OUT OF THE HOUSE SHOULD BE. ie.FROM THE BACK OF THE TOILET PAN TO THE OUTSIDE WALL, THEN DOWN TO THE MANHOLE. CAN YOU HELP!

[ALDA]

DAVID,

DEPENDS ON THE DIAMETER OF THE PIPE AND LENGTH OF THE PIPE FROM TOILET TO WHERE IT ENTERS VIRTICAL SOIL PIPE.

WHERE THE PIPE IS FOR SEWAGE ALONE A MODERATE FALL IS BETTER THAN A STEEP ONE.
THE LIQUID SHOULD NOT RUN AWAY LEAVING DEPOSITS TO FORM AND ADHERE TO THE DRAIN.(POTENTIAL FOR BLOCKAGES).

THERE IS A RULE OF THUMB METHOD OF DETERMINING THE FALL REQUIRED.
THAT IS, MULTIPLY THE DIAMETER OF THE PIPE IN INCHES BY TEN.
THEREFORE 100mm (4") PIPE NEEDS FALL OF 1 IN 40
150mm (6") PIPE NEEDS FALL OF 1 IN 60

HOPE THIS IS WHAT YOU ARE LOOKING FOR.

ALDA.