Minimum gradient of bath/washbasin waste pipe
 

Our bath/washbasin waste pipe emerges through the wall and then, via an
elbow, goes very slightly *uphill* for a run of a couple of feet, before
another elbow joint connects to a vertical pipe to ground level. The highest
point is probably an inch or so above the point where the pipe emerges
through the house wall, but as far as I can estimate, is below the level of
the bath plughole.

Is this likely to be responsible for water that is run out of the bath
ejecting the water from the washbasin U trap, or water from the washbasin
flowing into the bath and/or ejecting the bath's U trap wate, with copious
gurgling? And also causing very slow drainage of water from the bath
(several minutes to empty the bath).

I can see that even if it's not the cause of the gurgling and back flow into
the bath, it's not a good idea to have water standing in the pipe because it
will (and does!) freeze in cold weather: several times I've had to dismantle
the pipework and pour boiling water down the section that is normally
horizontal/uphill, to encourage the plug of ice to emerge.

Minimum gradient of bath/washbasin waste pipe
 

In message , NY
writes
Our bath/washbasin waste pipe emerges through the wall and then, via an
elbow, goes very slightly *uphill* for a run of a couple of feet,
before another elbow joint connects to a vertical pipe to ground level.
The highest point is probably an inch or so above the point where the
pipe emerges through the house wall, but as far as I can estimate, is
below the level of the bath plughole.

Is this likely to be responsible for water that is run out of the bath
ejecting the water from the washbasin U trap, or water from the
washbasin flowing into the bath and/or ejecting the bath's U trap wate,
with copious gurgling? And also causing very slow drainage of water
from the bath (several minutes to empty the bath).

Seems likely. The uphill bit has to be full allowing the flow to suck.


I can see that even if it's not the cause of the gurgling and back flow
into the bath, it's not a good idea to have water standing in the pipe
because it will (and does!) freeze in cold weather: several times I've
had to dismantle the pipework and pour boiling water down the section
that is normally horizontal/uphill, to encourage the plug of ice to
emerge.

--
Tim Lamb

Minimum gradient of bath/washbasin waste pipe
 

On Monday, 16 April 2018 21:21:35 UTC+1, NY wrote:

Our bath/washbasin waste pipe emerges through the wall and then, via an
elbow, goes very slightly *uphill* for a run of a couple of feet, before
another elbow joint connects to a vertical pipe to ground level. The highest
point is probably an inch or so above the point where the pipe emerges
through the house wall, but as far as I can estimate, is below the level of
the bath plughole.

Is this likely to be responsible for water that is run out of the bath
ejecting the water from the washbasin U trap, or water from the washbasin
flowing into the bath and/or ejecting the bath's U trap wate, with copious
gurgling? And also causing very slow drainage of water from the bath
(several minutes to empty the bath).

I can see that even if it's not the cause of the gurgling and back flow into
the bath, it's not a good idea to have water standing in the pipe because it
will (and does!) freeze in cold weather: several times I've had to dismantle
the pipework and pour boiling water down the section that is normally
horizontal/uphill, to encourage the plug of ice to emerge.

I have some experience with uphill waste pipework. It doesn't seem to impede drainage much - but if one section's uphill, the rest may also be badly laid out, causing slow drainage. Slow drainage plus uphill = collection of muck, causing partial blockage.


NT

Minimum gradient of bath/washbasin waste pipe
 

NY expressed precisely :
I can see that even if it's not the cause of the gurgling and back flow into
the bath, it's not a good idea to have water standing in the pipe because it
will (and does!) freeze in cold weather: several times I've had to dismantle
the pipework and pour boiling water down the section that is normally
horizontal/uphill, to encourage the plug of ice to emerge.

I would look to modifying that, it does need to have a constant fall,
to avoid problems of freezing and blockage from dirt. It is also bound
to cause the gurgling and slow drainage.

Minimum gradient of bath/washbasin waste pipe
 

On 17/04/18 07:41, Harry Bloomfield wrote:
NY expressed precisely :
I can see that even if it's not the cause of the gurgling and back
flow into the bath, it's not a good idea to have water standing in the
pipe because it will (and does!) freeze in cold weather: several times
I've had to dismantle the pipework and pour boiling water down the
section that is normally horizontal/uphill, to encourage the plug of
ice to emerge.

I would look to modifying that, it does need to have a constant fall, to
avoid problems of freezing and blockage from dirt. It is also bound to
cause the gurgling and slow drainage.

1:100 to 1:60 for turds

bathwater can be steeper.


--
Theres a mighty big difference between good, sound reasons and reasons
that sound good.

Burton Hillis (William Vaughn, American columnist)

Minimum gradient of bath/washbasin waste pipe
 

On Monday, 16 April 2018 21:21:35 UTC+1, NY wrote:
Our bath/washbasin waste pipe emerges through the wall and then, via an
elbow, goes very slightly *uphill* for a run of a couple of feet, before
another elbow joint connects to a vertical pipe to ground level. The highest
point is probably an inch or so above the point where the pipe emerges
through the house wall, but as far as I can estimate, is below the level of
the bath plughole.

Is this likely to be responsible for water that is run out of the bath
ejecting the water from the washbasin U trap, or water from the washbasin
flowing into the bath and/or ejecting the bath's U trap wate, with copious
gurgling? And also causing very slow drainage of water from the bath
(several minutes to empty the bath).

I can see that even if it's not the cause of the gurgling and back flow into
the bath, it's not a good idea to have water standing in the pipe because it
will (and does!) freeze in cold weather: several times I've had to dismantle
the pipework and pour boiling water down the section that is normally
horizontal/uphill, to encourage the plug of ice to emerge.

A Bing search for the words of your Subject line, without surrounding quotes, would seen to offer sufficient enlightenment.

--
SL

Minimum gradient of bath/washbasin waste pipe
 

It also pongs something terrible in hot weather so I'd at least try to move
the first elbow so its uphill not downhill of the other bend.
Brian

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"NY" wrote in message
o.uk...
Our bath/washbasin waste pipe emerges through the wall and then, via an
elbow, goes very slightly *uphill* for a run of a couple of feet, before
another elbow joint connects to a vertical pipe to ground level. The
highest point is probably an inch or so above the point where the pipe
emerges through the house wall, but as far as I can estimate, is below the
level of the bath plughole.

Is this likely to be responsible for water that is run out of the bath
ejecting the water from the washbasin U trap, or water from the washbasin
flowing into the bath and/or ejecting the bath's U trap wate, with copious
gurgling? And also causing very slow drainage of water from the bath
(several minutes to empty the bath).

I can see that even if it's not the cause of the gurgling and back flow
into the bath, it's not a good idea to have water standing in the pipe
because it will (and does!) freeze in cold weather: several times I've had
to dismantle the pipework and pour boiling water down the section that is
normally horizontal/uphill, to encourage the plug of ice to emerge.

Minimum gradient of bath/washbasin waste pipe