Can someone explain these liquid mechanics

[Shibam]

On my single player, i am using Minetek which is basically the yogscast mod pack, with BC IC2, biomes o plenty, and some other stuff.

My question is, the liquid flow doesn't stop in my world. For instance, i hit lava or water, it flows out or runs. Normally if i block up the main resevoir part, it stops flowing and goes away. But when i block it the running part doesnt stop. This means to get rid of the water i have to place a block at every location that it ran too.

Is this a common thing with these groups of mod packs like tekkit? Or an option or something?

For what its worth all other liquid seems to work, like i can take buckets of water out and it replaces the spring.