Rainwater Drain - Is A Trap Required (or Advised)?

[EViS]

We are laying some new paving and at the same time repairing some damaged clay pipes. The rainwater system is separate to the waste water system.

Do the rainwater drains require any form of traps? Or can the can downpipes from the guttering connect straight into an elbow (with a bit of straight pipe and a reducer inbetween)?

If a trap is required for rainwater drainage, what's the most efficient trap to install (the existing pipes are very close to the surface so can't have a trap with an outlet too low)?

 

[Hugh Jaleak]

If the rainwater is on a seperate system then the downpipes can be connected directly to the drain. If connection is to be to a combined (foul and surface water) sewer then a trapped gulley is required.

 

[EViS]

I'm thinking more along the lines of whether its advisable to have a trip to catch any roof debris?

 

[Hugh Jaleak]

If you require a debris trap you can fit a bottle gully. Outlet is quite close to the top of the gully, although you may need to protect the pipework with concrete if the shallow depth renders it vulnerable to damage.

Alternatively, a rainwater gully such as http://www.wickes.co.uk/invt/158828 will also do the job at about the same price.

 

[EViS]

If you require a debris trap you can fit a bottle gully. Outlet is quite close to the top of the gully, although you may need to protect the pipework with concrete if the shallow depth renders it vulnerable to damage.

Alternatively, a rainwater gully such as http://www.wickes.co.uk/invt/158828 will also do the job at about the same price.

What's the benefit of using a rainwater gully over a bottle gully?

 

[Hugh Jaleak]

Rainwater gulley has a bigger capacity for debris.

 

[Hugh Jaleak]

Rainwater gulley has a bigger capacity for debris.

 

[peekay53]

you are not supposed to use these gulleys for anything other than rain water clue is in the name so ideally there should be no debris in the gulley apart from leaf mould from gutt ers total tosh you need bigger gulley to hold more debris clean out twice a year and you will have no debris in there bottle gulley am sure you mean a back inlet gulley big that allows rodding access to the gulley but usually only used for kitchen sink waste washing machine foul water wastes talk about the blind leading the blind pay tradesman to the job properly and stop relying on ppl on these websites for bad information

 

[Hugh Jaleak]

I am quite aware of the rules regarding drainage. The OP clearly stated in the first post that the surface and foul drainage systems are seperate. The OP then asked about the need for a gulley for a rainwater downpipe. It is not strictly necessary, but if the OP wishes to fit a gully then that is their perogative.

Should the property be located under or near a tree then naturally there is likely to be more leaves and other detritus finding their way into the rainwater system. Therefore a gulley to contain the debris may be a sensible option. Which part of that do you consider to be wrong?

 

[peekay53]

all of it except what i said

 

[Hugh Jaleak]

you are not supposed to use these gulleys for anything other than rain water clue is in the name

The gulley is for rainwater.....

usually only used for kitchen sink waste washing machine foul water wastes

Bottle gullies can be and are used for surface drainage.

pay tradesman to the job properly

Clue is in the title of the website. Not everyone is in a position to afford to pay for tradesmen, if they feel confident to undertake the work themselves then why not? The OP was asking for advice regarding a matter he/she was uncertain about. Perhaps you would care to explain how you would do this?

 

[paulandfrodo]

I would always put a trap of some form in. Why risk blocking some pipe work you can't get to, without ripping up whatever you have just laid.