My house was built in 1986 on a concrete slab. Someone put a water filter on one of the waterlines coming out of the slab. I opened up the wall next to the water heater to see the water line. The filter does not filter the whole house, only the bathrooms. Does anyone know what the other 3/4 in line feeds and what those 2- 1/2 lines feed? I would like this filter to filter the whole house. Thank you!

That entire box shaped arrangement of pipes is simply a bypass so the filter can be changed without shutting down the water. I can't answer your other question because I can't inspect from this picture. Do you have hot water heat?

Yes, I have hot water. The 3/4 water line the filter is tapped into, goes to the hot water heater.

Bob nailed it,

The two vertical shut offs are in the open position allowing the water to be filtered.
To bypass the filter close the two vertical shut offs and open the one in the middle.
]This allows you to service the filter without losing pressure in the house.

I would like this filter to filter the whole house.
In order to accomplish this you would have to tear out every bit of piping from the filter and reconnect the water heater back to the system. Then take and install the filter, with a by-pass, on the incoming water service. Easier to buy another filter for the entire house and by-pass the hot water filter. Good luck, tom

Is the other 3/4 in line the incoming water service?

Again , its hard to tell from a single picture but I do not see any other cold inlet that would be feeding the rest of your home. It appears from this picture your entire house is filtered. Incoming 3/4" line is on the bottom then the filter bypass, that last 3/4 exiting to the left is the filtered water. Thoise smaller pipes appear to me are part of a hot water radiator system, maybe.

It appears from this picture your entire house is filtered.
I don't see it that way Bob,
Looks to me like the cold water supply to the heater was brought out, filtered and then brought back in to connect to the heaters inlet. What make you think that the 3/4" we see is the house main and not simply a 3/4" feed to the heater? Regards, tom

Here is a closer picture. If I turn off the filter and the bypass valve, I no longer have water to the bathrooms and one outside faucet. But I still have hot water everywhere.

If I turn off the filter and the bypass valve,
I don't think that's the way it works. You turn off the two vertical filter shut offs and open the bypass valve. Try it that way and get back to me. Can you tell ne something about that manifold I see? Is it hot or cold? Back to you, Tom

Yep, the position of the 3 gate valves shows filtered water. Give each valve a quarter trun and you have unfiltered water via the bypass. This new picture is a bit more clear, the manifild appears to be a cold supply to 3 different areas of the home.

I tried it again and it is just like I said. I turn off the filter and turn off the bypass and I don't have cold water in both bathrooms and laudry room but still have hot water. I still have both hot and cold in the kitchen. That manifold that you call it is cold water. Here is a better picture.
Thank you!

Show us a picture of the three valves after you made your attempt.

Here is all the valves shut off.

This is 100% correct for bypass. If you have no water flow with this configuration, but you do with the other, you have a clogged gate valve directly over the filter and it would be the first one I have seen. Carefully open the sharkbite on that center valve after closing your main.

Golfin62...

In your last posted image you said, "Here is all the valves shut off." That is incorrect... the middle valve is in the open position... ;) It is correct in terms of bypassing the filter, but all valves are not closed.

Are you on city water.. If so, look for a WATER METER... that will be where the main water feeds into your building. From there it appears that some of the pipes were run underground and some of the water gets filtered... some doesn't.

If you want to filter the whole house water supply, you may need to move that filter, but hard to say right now.

Find the main water meter (see images)... see if we can tell you more after that.

MARK

Our meter is out by the street. All the water runs under or through the slab.