Civil Code (Cap. 16), article 428

428. Each of the neighbours is bound to carry out in his own tenement such works as may be necessary to prevent any damage which may be caused to the party-wall by the cisterns or sinks existing in his tenement or by any flow of water or filth. CIVIL CODE [CAP. 16. 137 Ditch between two tenements is presumed to be common to both owners.