Electrics and gas
A vented copper cylinder is dripping at the inspection hatch and the immersion boss is crusted. What leak is visible, and what internal sacrificial anode was not pulled?
The visible leak is the drip at the inspection hatch of the vented copper cylinder, and the sacrificial anode inside was not pulled. The survey can see water at that hatch and crust on the immersion boss. It has not drained the cylinder, withdrawn the anode, or judged how much of the anode remains. A drip you can point at is not an internal inspection of the vessel. The home survey has not carried one out.
Last reviewed 24 October 2026. Written for buyers in England and Wales unless this answer says otherwise. No named surveyor has signed this page. It is general guidance, not a report on your house, and not legal advice.
What is the fuller explanation?
The hatch and the immersion boss are openings in the copper shell. Water at the hatch is a leak on the outside of that joint. Crust on the boss is a deposit where water has been before. Neither view shows the anode, which sits inside the cylinder to corrode in preference to the copper. Pulling it means draining the vessel and undoing the fitting. The survey did not do that, and it did not test the heating of the cylinder either.
Ask a plumber, not the home survey, to deal with the drip and to withdraw the anode if the cylinder is to be kept. Keep that quote separate from the report. Tell the solicitor the finding is a visible drip and crust, not a verdict on the life of the vessel. The survey has not signed the cylinder, and it has not performed a gas or electrical check of the heat source.
What should you ask your surveyor?
- Was the visible leak the drip at the inspection hatch?
- Did crust on the immersion boss stay an external observation?
- Was the sacrificial anode left inside and not pulled?
What are the typical next steps?
- Describe the drip at the hatch and the crust on the boss.
- Do not treat that view as an inspection of the anode.
- Ask a plumber to address the leak and the anode if the cylinder stays.
Costs vary with the building and with who you instruct. Where this page does not cite a published figure, ask the surveyor, a relevant specialist, or your solicitor for a written quote. Do not treat a forum average as the price.
Also asked about this
If the drip is slow, is the cylinder sound inside?
No. A slow drip still shows a leak at the hatch. It says nothing about the anode, which was not pulled, or about the inner face of the copper, which was not seen. The survey has not looked inside the vented cylinder at all. Crust on the boss is separate from that internal view.
Does crust mean the immersion heater was tested?
No. Crust is a deposit on the boss. The survey did not electrically test the immersion, and it did not withdraw the fitting to look inside. A stained boss is something you can see from outside the cylinder. It is not a test of the heater or of the anode.