On my Pennine pathfinder 2003 the O ring were you connect the Water pump to the camper has before very loose so therefor when the water is pumped it gets air in it and water leaks out aswell
Does anyone know what side i need or could point me in the right direction ?
Lidl's & Aldi's from time to time sell O Ring kits which cover most sizes and thicknesses.
If you see them for sale, get a box. They will last you for years and will cover every eventuality.
I tried using an o ring from a generic selection box kit. It had the correct diameter but the o ring was too fat.
You would be better getting the correct ones from eBay, Amazon or a dealer accessory shop. Add a little olive oil when inserting for the first couple of times too.