1 of 2 products will have been used to deep clean the toilet on G-JEBC.
Honeybee76 is used during overhaul in workshops , and Aqua Kem Blue is used as a pre-charge prior to the aircrafts departure from c-check. Aqua kem blues manufacturer website describes it as so:
"
AquaKem blue fluid is a formaldehyde based product whch is proven to be the most effective liquid chemical for re-circulating and fresh water toilets."
the aaib report (which i just read after writing all that) describes it all in clear detail