Post title is self-obvious, but to give an example...

Let's say I enter Riverwood at the beginning of the game. I pick up Faendal as a follower after settling the issue between him and Sven in Faendal's favor.

Now... I go to Faendal's house to pick up some spare equipment, and there are a bunch of chest and containers in Faendal's shack. The question is whether or not these containers (such as the chest) are "safe", meaning that they won't respawn contents in two game days, thereby costing me whatever I put in there. After all, I have to figure that, if Faendal is with me (until I get a house and a housecarl as a companion), then there shouldnt be anyone going in to Faendal's house and messing around with his (or my) stuff.

Any chance I could get a ruling on this from an official? Also, would the same apply to houses of any other companions I pick up in the game?

No,,,

I left some items at my wife's house to test if it was safe and when I left her house and re-entered to check, they were gone.

Unless its just a PS3 glitch. I was hoping not to have to buy a house so early on. lv1 with zero gold to my name lol

Might be a PS3 glitch. I'm on the 360 and I've married Ysolda on multiple characters before ever buying a house and stashed all my loot in her house for months (in-game) without it ever going poof.

it was Ysolda's house I used to... maybe a glitch with that character. will have to try with another.

I did the same and never lost anything.

I've also stored stuff in the barrels outside of Warmaidens and never lost it. Same with the barrel outside Arcadia's Cauldron. However, my kid lost all of her stuff from doing that so beware.

I'd be real careful.
Officially, the only safe containers are in homes you purchase (of course there are isolated exceptions to this). That said, cells only reset after the allotted time elapses after you leave them, so for example, if a dungeon is cleared, it will reset in 30 days, but every time you visit it within that time frame, it resets the countdown timer. Theoretically, if you keep visiting a cell within the respawn time, it will reset and restart the countdown from the last time you visitied (does this make sense? I feel like I'm talking jibber-jabber) so your stored items will remain intact. Beware of unclearbale locations with a respawn time of 10 days! See this page for the source of my jibber-jabber: http://www.uesp.net/wiki/Skyrim:Respawning

Well, since the companion thing is out, it seems like the quickest way to acquire a "home" (if you want to call it that) is to get to Riverwood & use the house of whichever couple you are introduced to (Stormcloak or Imperial allegience) as a TEMPORARY measure. Once you're set up, hie thyself quickly to Whiterun (particularly the Stables) and take a wagon ride to Riften. Do two missions of the Thieves Guild... and voila: a bed, a chest and an end table, the latter two being "safe". Don't forget to go back to Riverwood and collect any loot you left there.

Before I had a house I kept all my stuff in Sven's house in his trunk, dresser and night table and it was all there when I went back.
Now I need another trunk or two at my house.

I'm on PC, BTW.

I am not an official, but my understanding is that some types of containers do not respawn. I have used the cupboards, dressers, endtables, and wardrobes in followers’ houses without losing anything. I avoid the chests, sacks, and barrels. When I want to place an object somewhere for a decoration, I avoid the spaces already occupied by the follower’s stuff.

Here’s my source: http://www.uesp.net/wiki/Skyrim:Containers

Safe locations are fairly well documented in the UESP wiki. Faendal's House is not considered safe. Respawn time is 10 days as expected.

http://www.uesp.net/wiki/Category:Skyrim-Places-Safe

http://www.uesp.net/wiki/Skyrim:Containers#Safe_Locations

Although I'd not use them as permanent storage, most barrels scattered about towns are safe. If you walk up to one and it doesn't say "steal from barrel" chances are you can use it all you like. The ones outside of Warmaidens in Whiterun are a good example, plus those across the way at The Drunken Huntsman. I've temporarily used the barrel outside of the shop in Riverwood, too.

However, your best bet is to use the containers in a house you purchase. You can also use those of your spouse's home, which become community property. Not sure if you first have to do that "visit your spouse's home" thing, like to trigger "lover's comfort".