The results of site investigation and a series of tests in laboratory & in situ reveal the development condition and progress of physical, chemical and biological cloggings. On the basis of engineering practice and the revealed mechanism, a few treatment measures for clogging, including the relief well with a replaceable filter, are devised and tested in laboratory and in practical engineering. The results demonstrate that some of the treatment measures are effective and maneuverable. It is pointed out that relief well clogging could be avoided or mitigated under the conditions of reasonable design, construction and operation. The clogged wells could recover function again after being dealt with some measures. It is proposed to apply extensively the relief well with a replaceable filter.