I want to use a Sea to Summit 20L collapsible bucket as a reservoir for a gravity feed water filter. Any ideas on how to add a bulkhead that will sit kinda flat on the bottom of the bucket so I can still use the bucket as a bucket?

try as i could, just couldn't find a pic of the bottom of one of these...so, would a 90 dregree bulkhead fitting do? thee bottom rim would be sitting on the hose, but if there's any kinda rim, it should work

I was thinking about this more, I would be better off to put the bulkhead on the side of the bucket, near the bottom. It would make it easier to use the bucket as a bucket, and with dirty water, you could hang the bucket overnight and let the silt settle into the small space under the bulkhead before filtering.

The Sea to Summit bucket is TPU coated nylon. Isn't that the same coating that is on heat seal-able nylon? Could I use an iron to bond the bucket to the bulkhead then?

Ray, I would be wary of heating that fabric. TPU varies a lot, and some compositions are for heat-sealing and some aren't. Even if the TPU on that fabric would work for heat-sealing, it would only seal to another TPU with a similar composition and a similar softening/tack temperature range. It wouldn't bond to a dissimilar TPU or any other material. I've tried that.

If you try to use heat, it is more likely that the coating on the bucket will peel off and your bucket will no longer hold water. If you want to bond something to that fabric, I would recommend urethane glue.