Gaiters won't stop your boots from leaking; they protect your lower leg. They are great for walking through heather or across rough moorland, though.
Back to boots... I bought a new pair Lowa Renegade boots in Austria last time I was there. Gortex lined, very light and comfortable but I expect that they will eventually start to let water in as they wear. I always carry a spare pair of thin walking socks and a pair of Gortex boot liners in my rucksack. If my boots let in enough water to be uncomfortable as they have done when I've had to get across streams from time to time, then I can dry my feet, slip on the dry socks and boot liners and carry on with perfectly dry feet.
John
Age and treachery will always triumph over youth and ability.