Abstract: A standing valve wash-out tool comprises:A. a vertically elongated tubular body,B. elastomer cup means on the body to engage a well tubing bore as the body travels lengthwise within said bore in response to fluid pressure exertion on the cup means exteriorly of the body,C. the body having a fluid pressure inlet above the cup means, there being a frangible plug within the body blocking fluid pressure flow downwardly through the body, andD. a seat on the body proximate the lower end thereof and sized to land on sand containing means, whereby application of sufficient fluid pressure within the body will rupture said plug and pass downwardly through the body and outwardly below said seat to wash sand from said sand containing means.