My grass pitch holds water and needs drainage, what is the process?

The first step would be to complete a Pitch Power test if you have not already - Football Foundation | PitchPower 

Following completing a test you will get a report back from the Regional Pitch Advisor which will highlight a list of recommended actions including improved maintenance works and suggested machinery and possible funding available for the works through Grass Pitch Maintenance Fund, details: Football Foundation | Grass Pitch

The Football Foundation would usually like to see a club try improved grass pitch maintenance work being carried out over a period of 2-3 years to see if that alleviates the issue before considering any drainage projects.

If after this period of improved maintenance works the issues persist then contact your county FA for support and advice through [email protected] on how to proceed