Waste tank vent line filter

[Chona]

I have an ‘88 Carver 3607 aft cabin with two heads. Almost immediately after a pump out, their is an odour on the dock when we pump flush the toilets. I was told their was a vent line filter that need to be changed and have looked all over the place for them. Does anyone know which hatch or area one or both are? We have an over abundance of deodorants and cleaning materials so that’s not the problem. Thanks in advance for any suggestions.

[g36]

Lots of discussions on the forum about this( try search feature) there is probably no filter , these weren't always installed. If you followed the venting out to the hull fitting and found nothing then you don't have one. You can always add one or make your own. Allso see some suggestions if you search holding tank filters.

[km1125]

I doubt you have any filters, unless a previous owner installed them. If yours is like my earlier 3607 (an '83), then you have two waste tanks. One is located under the rear seating in the dinette and the other is under the aft berth. You can remove the hatches under the mattress in the aft berth and follow the vent line from the waste tank (which is the one in the center, just forward of the water heater) back to the vent, which is in the transom just to the port side of the berth (under the cabinet on the port side**). In the dinette, you can remove the hatches below the cushions and follow the vent hose from the tank towards the port side vent, right near the bulkhead.

But I wonder why you only indicated the smell was after you do a pump out. If you don't have filter(s), then you'd likely smell things anytime after you flushed a head, as that would push some "fumes" out the vent for the respective tank.

The only real difference "pre-pump-out" to "post pump-out" would be that the lower hose is full off effluent. Is it possible that your deck fittings are missing o-rings and that's where the smell is coming from?

EDIT: ** There are two vents in the transom. One is for the potable tanks and one is for the waste tank. I forget which side either one takes. One goes to the port side vent and one goes to the starboard side vent.