Who Has A Berkefeld?

[Lightspeed]

the neoprene grommets sound like a good idea,

Not sure about the silicon though. there's a fair amount of pressure there when the reservoir is full

You can get neoprene blanking grommets from plumbing supplies, they are often a red colour compared with rubber grommets which taint the water. Alternativel if you are blanking the holes of until TSHTF you can use aquarium silicone sealant ( the type without fungicide in it)