LowWater - what is the relevance of this?

I saw in the docs, it is set to 600 and the docs state it is the minimal number of connections to maintain. But in the sample config I have out of the box, I get lowWater set to 600 which is very high as a I have a private network and only a small number of connections. Hence should I just change this to 3?

ThevLowWater mark is just the number of connections IPFS will actively try to obtain. The more you have, the faster your queries since you ask to more peers, but the more ressources it takes. IPFS can open more connections in other circumstances (if another node connects to yours, for example). It will start clean connections (close some) when it reaches the HighWater mark. If you have a private network with only a few nodes, you can lower you LowWater to avoid IPFS trying to open more connections it can’t open for lack of additional peer in your network.
But anyway, your node should be able to work properly even with a connection count below your lowWarer. It will just actively try to open more.