Don't drink from radiators

[NorthernRaider]

The sludge comes from anaerobic bacteria and disolved metals from the system such as copper, iron, zinc etc, remember some heating systems treatments contain heavy metals and carconogenics.

---

Note that when you have to frequently bleed air from your radiators but you know its not leaking its because the gunge in your system is producing hydrogen sulphide, so imagine the shite in the water !!