Bathroom sink smells strongly like sewer when water runs fast.

When you next get the smell, check the traps to see if there is enough water in there to fill the trap, if one is less then it looks like water is getting sucked out when toilet is flushed or that trap (usually bath or shower) hasn't had water going in (lack of use) and water has partially evaporated.

try running all the water in the whole house at once. all toilets. outside faucets, washing machine, ect...
assuming you have no leaks.

It is possible that the vent pipe behind the toilet is clogged (or was not installed properly). Some bathrooms are set up with one shared vent pipe, and a clog in one of the lines leading to it can cause similar problems.
The vent pipe in each bathroom does 2 things:
1: it lets the sewer gas go past the bathroom and up out the roof so you don't get sewer gas in the house.
2: It breaks the siphon as water goes from fixtures down to the big sewer pipes in the house. If it isn't working for a sink, it's not much of a problem because air gets mixed in with the water as it does down the sink, and this breaks the siphon. But in a toilet, it jsut keeps pulling water down the pipe until the water level in the toilet gets low enough to let air into the pipe, breaking the siphon.

It's not an easy problem to fix and often involves removing walls to get at pipes.
A plumber can bring a snake tool and try clearing the pipes from below or from the roof, and might even be able to bring a steerable snake that lets him control how it goes through the pipe.

Ensure all your additional rough in plumbing is capped, and toilets or sinks that are not used for long periods of time , sometimes p traps may dry up allowing sewer gasses to enter the home so use them once in a while or fill with water once in a while ,same with floor drains. If that isn't it check that you have them installed.

sewer gas is stopped by water in the drain. often three drain I. the floor dries out. or your drain is not holding water. pour water into all your drains. .

Sounds like you have an intermittently blocked vent pipe (the one that goes out through your roof). If there is gas pressure in the downstream sewer line and it can't get up through the vent, it could bubble up through your toilet or sinks. I would get up on the roof with a few jugs of powerful drain cleaner and dump them into your vents. You might also run a few dozen gallons of water down those vents after the drain cleaner has had time to work.
Good luck!

The smell may be coming from the sink trap if there is a problem with the vent pipe (that's in the wall from the sewer line to the roof). Do you ever hear gurgling in the sink drain when you flush? When you have the smell again, stick your head in the sink and see if that's where it's coming from. If you have a floor drain, the smell may be coming from there. In either case, a bit of water added to the drain will fill the trap and stop the smell. Please vote if you found this helpful. Good luck, Al K

It sounds like a vent problem.
On top of each house is a vent stack.
There should be a vent stack above each toilet, and above kitchen sink.
Look for pipes sticking out of roof.
These pipes are open to the sewer line.
When you run a column of water down a drain, the vent stack lets air flow in front of and behind the column of water.
This air flow prevents the gurgling sound.
The gurgling sound is the drain water pushing air in front of it because of a clogged vent.
If you have a two story house, there are vents that run between floors to prevent the air flow from gurgling or bubbling sewer air into each drain as water column moves down pipe.

http://www.bradyinspects.com/plumbing-vents.html
http://chestofbooks.com/home-improvement/construction/plumbing/Standard-Practical/Venting-Part-3.html

Look for bird nest over vent pipe on top of house.
Run a snake down into pipe from roof and see if the is a stoppage.
You many need to call plumber to track down each vent and the cause.
For example if there are quick-vents installed inside a wall and the quick vent is no longer working.

You can also take advantage of fixya phone support.
Fixya expert will walk you through the steps for a price.

Fowl smells related to plumbing can have several causes. Here's a few potential issues that you can check. If none of them solve the problem you may need to call a plumber.

1) Look at your pedestal sink drain connection. Is there an an elbow connecting to your drain or a P Trap? A p trap is a pipe shaped like the letter "p" (hence the name) and it prevents sewer gas from rising into the bathroom. **sometimes an apprentice plumber puts in a pedestal without a p trap because they are fairly difficult to install, and ALL fixtures need P traps. If there is no P trap, then you need to put one in. It will be a tight space, but you may be able to do it yourself.

2) Do you have a floor drain? If so, your sink will need a trap primer at the drain. Or you can pour water into the drain from time to time before it evaporates from the trap

3) If the smell is more of a sulfur type smell and it appears from running water in other places in the house, then it could also be due the type of tank you have if you are on well water

My offhand guess is that number 1 is your issue.

Without further info, those are some of my best solutions so far, but if none of these are potential solutions, then make the following tests

1) close the door to the bathroom and leave it for an hour or two. Return to the room. Do you smell sewer smell? Is it in the entire room or more concentrated in a certain area? If you don't have a floor drain and its everywhere, there could be a missing P trap from a fixture, a lose toilet flange, a cracked drain pipe
2) without running water, smell your drain. Does it have a sewer smell? Then the P trap either is not present or you need to clean the drain with a drain cleaner due to a list of reasons
3) run water. does the sewer smell increase or does one suddenly appear. Is the smell more a different odor than sewer. See if it is the water itself. If so, check other places. If they do not have the smell then you may have recently installed your sink and there is some smell related to the new valve. Then you would need to use it some more until it disappears.

Check the top list, though because I really think you're just missing a P trap

Sewer breaks below the slab, an open pipe somewhere, some issue with the water supply, are among some other issues but that depends on the test