Smell from sink

Plug the outlets and pour a milton mix down sink and leave for a while,if waste pipe is the corregated flexible type pipe it may have "dips where waste water can lay 

Is this in a trailer caravan or a motor caravan? 

With both, many people use an additive to the waste tank to prevent this - bio-tabs from Aldi/Lidl seem to be quite popular and effective.

I think the trick is to avoid putting greasy, mucky water down the plug hole to start with. We carry our dish washing water to the disposal point and it seems to work on the whole.

Once or twice our tank has been a bit pongy and it was easily fixed. Pour a whole bottle of cheap disinfectant down the plug holes - divide it between them - then pour down a couple of kettle fulls of hot water, take the MH for a drive to shake it all about and then drain the tank responsibly.

Correct, Tinny, trick is never to let fats or food particles go down the sink. Use a bowl and empty such directly into the service point or portable container. We learnt the hard way, onboard tanks needed a thorough clean and pipes decreasing with our first van. Never again!

 AND     leave the plug in  !!.

I was amazed that on my nearly £100k motorhome that there was no stench traps fitted to the sink, shower and wash handbasin. When I queried this with the manufacturers I was told that overwintering and frost protection made water traps a potential for frost damage. Have to say I was not satisfied with this answer but it seems that this omission is pretty much normal on UK built motorhomes.

The advice I was given from a variety of sources was:

Clean plates etc of food debris before washing in the sink.

Avoid pouring anything with a diary content into the sink and definitely no fat or oil.

Crumble a bio (cheap) dishwasher tablet into the waste tank via the sink/shower/hand basin after the tank is emptied.

Use a sank sanitiser (Thetford etc) according to the instructions on the bottle after every waste "dump".

Always leave the plugs in position.

All this sounds complicated but it is not really and after a period "it" becomes second nature. Doing the above above has worked for us even during extended periods in Southern Europe with ambient temperatures in the late 30c's

Ome "n" Dri

I fill the system up with hot water and dishwasher powder twice a year, leave it soak a bit, take it for a drive, then flush again with hot water.

As newbies to the motorhome (after caravanning for 30 years) we were delighted that the built-in waste tank would last for about 7 days. Big mistake! The smells build up and are much more difficult to remove than emptying the waste more frequently!

The only thing that doesn't get tipped down there is fat. Some is unavoidable from greasey plates and frying pans. Always drain down when leaving a site, don't store the van with grey waste still present in the tank and chuck a bio tab down now and again as explained above.

peedee

All good advice. We can understand why no traps, our weather gets down below freezing quite regular, sometimes seriously below freezing! Using a wash up bowl and being careful about what goes down pipes is by far best advice, empty often as well. We occasionally use white vinegar to disinfect our pipe work and tank, poor in, plug up, take it for a bouncy ride, then empty and rinse out. Vinegar doesn't smell.