Spring water and moldy taste and smell

My family and I moved into an 1850 farmhouse about 3 weeks ago and, from the start, I have noticed a moldy odor to the water coming from the tap and the water sitting in the toilet bowls. I can't stand drinking it, the flavor is there, but we all have been. Anyway, our system is spring fed. My husband checked the spring house and, aside from a toad swimming around up there, things look clear. In the cellar, the water is captured by two 65 gallon plastic tanks. An electric pump sends the water through 4 filters, including a UV filter, before coming up into the house. My suspicion is that the problem is located in the tanks, but I'd love to hear others' thoughts. What could be causing this issue and what should we do about it?

My suspicion is the filters.  How long did they sit unused before you moved in?

Since the spring house looked clear and did not smell. I would remove the first filter flush a couple gallons and take a sample of the water from the pipe.  Now you know if your issue is outside the house or inside.  I suspect a new set of filter cartridges is in order.  Tom

Tom's advice is good -- isolate the problem.

I would also take a sample from the spring house and let it sit for a few days in a clean jar (covered with a cloth but not sealed). Then do a nose check.

get a jumbo berky for drinking water and never look back

Water tank, filters and pipes within the house could all be causing the problem.

What are the pipes made out of?

Has the tanks been drained recently?

And as Tom suggested when were the filters replaced?

And I like the suggestion by Bruce to get a Berkey:

https://myberkey.com/collections/filter-systems

If you find fine sediment in the filter system, install a much bigger collection tank.
This will enable suspended matter to drop out, if it is kept still for a longer time, than just passing through to your filters.
Also have the water discharge pipe floating just below the water surface to get the cleanest water from the tank.
floating-out-take-40mm-hose/ebpage

We changed the filters and that helped right away! The last owner said he'd just changed them so we had left them alone, but the house sat empty for a couple of months before we took over. Went down there with all new filters and, turns out, one of the filters was pretty gross. Hopefully, that was all that was needed for now. We will take all of your suggestions for testing and how to improve the system into consideration as we move forward. Maybe switch to a stainless steel tank too? I will have to mine this site for more water system info.

Thanks everybody! Have a good February!

Thanks for the update Nikki, It's good to get feedback on a result!

Nikki, the state of the filters indicates that solids are not settling out in your barrels.
A change of volume, not construction material is the only way to get this happening.

A friend had a similar water issue at a house they had just bought, and it was also the filter that ended up being the cause.

I would also concur with the above about settling tanks. Ancient Romans discovered that the larger the cistern and longer the settling time, the purer the water in the middle-center of the water column.

Some folks suggested Berkey filters -- impressive reputation.

I recently read that new filters are hard/impossible to get. I don't know if that's true but I personally would use a dozen cheap filters first, and Big B as the last line of defence.