Anyone know what this is?

Can anyone tell me what this is, we where cleaning outside and we found this, the valves going to this canister is shut off so no water was going through. This is line feeds the enyire house but the canister is bypassed. I tried unbypassing it and turned on faucet beside it and stink water came out, we've been here for 7 years and this is the first time i've seen it.

Thanks

 

Looks like a filter cartridge. The blue lower portion should screw off and there will be a filter in there. I have two on my water system. If it was bypassed it would be full (or at least was before it evaporated) of stagnant water. You could take out the filter and let it run to clean out the lines and try any plumbing store for a replacement filter. Or I guess if you've made it this far without it, you can continue on without it lol.

 

Thats what i thought, just dont know what type of filter, guess i'm gonna have to open it. Wonder if theres any media that would soften the water a little that would fit that thing.

Thanks

 

It looks like the name brand big blue, probably just a sediment or a carbon filter in it.

 

I would say its a sediment filter or carbon as well. My filters look like spools of yarn, these are sediment filters.