A technique is described in which a web service provider is able to specify that messages related to business transactions with the web service includes trading partner information. The surfaces of the integrated elements, provided for coming into contact with the potable water, are at least partly provided with a finish which is effective against microbes andor fungi. Then, the corrected stratified mode fuel pressure value is compared with a current fuel pressure value, then a final fuel pressure value is obtained according to the comparision result. The reaction is carried out in a vapour or in a liquid phase. Preferred water-soluble polymers include polyvinyl alcohols and polyalkyl oxazolines. The phenol may be, for example, a cannabinoid or a catechin compound.