We lived in California where it hardly ever rains except in the winter and early spring. I can count on my one hand when we had serious rain during camping in the past here. Therefore, when purchasing a tent, waterproof was never a high priority. Typically we would go with a 3-season tent as it is usually cheaper and lighter and has more choices than a 4-season tent. We purchased a REI 3-season 4-person tent 2 years ago when our old tent were literally torn apart in a sandstorm in Death Valley.
We knew that we might encounter more rains in the East therefore we ditched our Yakima Basketcase in favor of a hard-shelled cargo box. We didn’t think more about our tent as it seemed to work okay on our camping trip to Northwest the year before when it rained a couple of days. We had about 4 days of heavy rains during the time we were camping on the trip and every time, the water seeped in from the bottom. I was disappointed with the REI quality but my friend, Mike, told me that 3-season is not waterproof guaranteed; only the 4-season is.
The 1st couple of times were very bad: most of our sleeping pads were wet. I reflected on our trip to the Northwest and realized the difference was that we had a tarp on this trip. We didn’t have a tarp designed for the tent; it was a plastic all-purpose 9×12 tarp for weather protection. Water got collected on it and became a puddle underneath our tent. Then throughout the night, water seeped through the floor. After I realized the problem, I made effort to fold the tarp to the shape of the tent if it was raining so it wouldn’t collect too much of rain. It helped quite a bit as leaks became smaller.
Now I understand why people would pay for a special tent tarp which has a footprint the exact size as their tent. There is usually a reason for everything. Sometimes I am too stupid to realize it until a situation arises; then it becomes embarrassingly obvious. I think I will go for a 4-season tent next time I go somewhere it may rain a lot: wet sleeping gears are not fun.