Into the cabinet
Filter housing and manifold
The fitting the cartridge twists into, and the reason a filter change can end in a drip.
- What it does
- The manifold is the fixed fitting the cartridge twists into: it holds the filter in the water path, seals around it, and hands the flow on towards the inlet valve. The cartridge is consumable; the manifold is not, and it will outlast many of them, provided it is treated as a sealing surface rather than a handhold.
- Where it sits
- Wherever the cartridge shows itself: behind the grille at the top of some cabinets, behind a small hinged panel high inside the door on others, and low on the inside wall of an undercounter ice machine. The body of it is out of sight in every case.
- How it is tested
- By doing the change and then watching. A fresh cartridge goes in clockwise until it seats — there is no click, and a little movement afterwards is normal — and then the manifold gets a dry cloth under it and an hour of attention. A housing that drips only under fill pressure will stay dry for the first forty minutes and give itself away on the next cycle.
- What the work costs
- Ice maker, water valve or supply line: $300–$820, after the flat $89 diagnosis.
Pattern
What we usually find
- A cartridge that was never driven fully home, so the seal is only half made and water escapes around the collar every time the valve opens.
- A non-matching cartridge crossed into the thread. It turns far enough to feel right, then sits proud, and the manifold takes the damage rather than the filter.
- Scale on the sealing face, left behind by years of hard water, holding the cartridge a fraction off its seat no matter how firmly it is turned.
- A hairline crack in the plastic body, usually at the thread, which weeps only while the ice maker is filling and stays dry the rest of the day.
Most often first. Order comes from what the visits keep turning up, not from a count.
Almost nobody thinks about the manifold until a filter change goes wrong, and then it is the only thing worth thinking about. It is the part the cartridge is torqued against every time one is changed, with whatever cartridge came out of the cupboard.
There is water held inside a cartridge, so a small spill when the old one comes out is expected rather than alarming. What is not expected is a wet patch still there an hour later, or a stain that returns between changes — those belong to the fitting, not to the filter.
Repair or replace
What usually happens to it
Replaced, and as an assembly. The thread and the sealing face are moulded into it, so a manifold that weeps around a correctly seated cartridge has nothing on it to tighten or renew. Cracks tend to start at the thread, where somebody forced a cartridge that was never meant for it.
Two follow-ups
Is a drip at the filter the cartridge or the housing?
Fit a second, correct cartridge and seat it firmly. If the drip stops, the first one was the problem; if it continues, the manifold is. That single test saves pulling a built-in out for something a two-minute change would have settled on its own.
Can the housing be changed without pulling the unit out?
Usually yes, because the manifold is reached from the same opening the cartridge comes out of. Denver Sub-Zero Repair Experts decides that on the visit rather than over the phone, since a cracked housing sometimes comes with a sodden cabinet base that has to be dried and looked at first.