Unusual contamination resembling biofilm or mould was causing concerns about health for the occupant of a stylish inner city apartment situated in larger period build building complex. The apartment is situated in the first floor and consists of kitchen/dining area, 3 bedrooms, 3 toilets and a central corridor. The apartment was situated in inner city London and is surrounded by properties of a similar type. Prior to the inspection the property occupants have reported symptoms such as headaches, itchy eyes, runny nose and general respiratory irritation.
I have carried out a comprehensive inspection of the apartment which in my opinion was in perfect state. The moisture investigation did not identify any areas with elevated moisture content.
I have been asked to investigate a sort of black residue accumulated in the shower heads in the main shower room. The microscopic examination of the residue showed that the black residue is of biological origin and most likely detached piece of bio-film from within pipe work or a water storage vessel. Examination of water storage vessel (toilet cistern) in the apartment did not show excessive accumulation of microbial bio-film above the level which would normally be expected. Two large water storage tanks are located on the roof of the building supplying the utility water systems. One of the tanks was lined with bituminous black lining which appears to be deteriorated in places.
On the request of the client I have carried out mould spore sampling in the apartment. Evaluation of the collected samples showed that indoor mould concentration was significantly lower in comparison to the external background sample. The indoor samples were dominated by Penicillium and Cladosporium mould spores with lesser presence of fungal fragment and Chaetomium spores. Viable mould samples were dominated by various species of Penicillium mould at or below the concentration recorded on the background sample.
I have concluded that the black deposit in the shower head most likely originates in pipe work network or water storage vessel. Small amounts of residue in utility water are not hazardous to health. In house chemical analysis of the utility water from two toilet cistern show very high mineral content. The water can be described as very hard. Mineral deposition on porcelain surfaces is most likely responsible for frequent staining of porcelain surfaces.
By Tomas Gabor
