- Do not empty the water from the siphon but on the contrary, raise it to the highest level by gently pouring water.
- Pour (in the evening is good) the value of a good glass of hydrochloric acid.
- As a precaution, however, be careful not to splash the seat or wipe it. Likewise, close the lid and leave the bottle (or a clearly identifiable index) on the lid.
- Leave to act, depending on the layer of tartar, for between 5 and 30 minutes.
- When all the scale is dissolved by the acid, foam no longer forms.
- Give a little brush stroke.
- Flush.
NB: Hydrochloric acid is not polluting or dangerous because once in the wastewater network, it is instantly diluted in proportions which make it completely inert…!