Abstract: Drainage well is a widespread application of seepage control in water conservancy projects. However, the well is prone to clogging. To extend its life, a removable filter is applied to the drainage well according to the research findings of clogging. The working principle is to make part of physical clogging or most of chemical and biological clogging occur in the removable porous foamed plastic filter which is placed in the drainage well. The filter can be taken out to clean or alternate to regain its drainage ability. The applications in dam foundation drainage holes, relief wells of dikes and horizontal drainage holes of channel banks show that the removable filters can extend the life of drainage wells significantly and their future is prosperous.