It is possible to install a new check valve between the pump and the existing piping to address a leaking foot valve in a well. However, there are a few factors to consider before making this decision.
First, it's important to determine the cause of the leaking foot valve. If the valve is simply worn out or corroded, a new check valve may provide a temporary solution. However, if the problem is caused by a deeper issue with the well, such as a damaged or collapsed well casing, a new check valve may not be sufficient and drilling a new well may be necessary.
Additionally, it's important to consider the age and overall condition of the well. If the well is old and showing signs of wear, it may be more cost-effective and less risky to drill a new well rather than attempting to repair or replace components.
Finally, if you are not comfortable working with wells, it's best to hire a professional plumber or well driller to evaluate the situation and make recommendations.