Water pump keeps cycling when all taps are off - help!

Bit of a strange one - our water pump has started cycling on and off every few minutes even when all the taps are firmly closed. It's not constant, just a brief buzz every couple of minutes. No signs of any leaks that I can see. Anyone experienced this before? Is it likely to be the pump itself or could there be a tiny leak somewhere I'm not spotting?

Could be a few things. First, check your toilet cistern - sometimes they can have a slow leak into the bowl that you can't easily see. If the cistern is constantly refilling, that'd explain it. Second, check all your pipe connections under the van - a tiny drip might not be visible inside but the pressure drop will trigger the pump. If you can't find any leak, it could be the pressure switch needs adjusting or the non-return valve in the pump is failing.