Do shared albums use storage on your hard drive?

If you're referring to "Shared Photo Albums" the answer is NO. If you created the shared photo album then you already have the photos on your hard drive in your Photos library. If you delete those files from your library they will remain in the Shared Photo Album that you created.

If the shared album was created by someone else the photos will not take up space on your hard drive unless you import them into your library.

According to this Apple document one can view a shared photo album with having them on their hard drive: iCloud Photo Sharing FAQ - Apple Support

Can photos and videos be saved or downloaded from a shared album?

Yes. After photos are shared, anyone who can view the shared album can download and keep them permanently.

That seems to indicate that you can view without downloading and taking up space on your hard drive. From my recent tests just now if you create a Shared Photo Album and then delete the photos from the library that were used to create it they photos will remain in the album, both in Photos and online.

Even if you do delete the photo from your library each time you open Photo app it will download a copy of all your shared photos locally (this being separate from your library). Therefore, if you didn't delete that photo form the shared album you would technically have a duplicate of the photo.

This is the problem I am having as I have a mac air with only 128GB and have moved my photo library to an external but still find local copies of my shared photos every time I open Photo app. I have deleted these each time as it uses up in excess of 40GB of hard disk space but each time I open Photo app i find them all back on.

I have spoken to apple who have told me that to avoid this local copy (from the shared album not your library) I can turn off iCloud Photo Sharing (streams, photos and shared albums included). The problem with this is that then I cannot view them even on the website because you have to have one device with it turned on.

If someone can help with this conundrum it would be greatly appreciated!! 🙂

If you enable "System Preferences > iCloud > Photos (Options : iCloud Photo Sharing)", the Shared Streams will download to a folder in your User Library. They are not included into the Photos/iPhoto/Aperture Library unless I import them.

I am seeing all my Shared Album photos in the folder

~/Library/Application Support/iLifeAssetManagement/assets/sub-shared/

The image files in this folder are reduced in size, about 2085 × 1536 pixel.

I am confused. It sounds like accepting someone's Shared Album does take up local HD space but not in Photos but rather in Library with a reduced pixel size. Is that correct?

If accepting Shared Albums take up space then:

1. How can I delete or stop accepting photos coming in to me from someone via Shared Albums?

2. If I stop accepting or delete the subscription to their Shared pictures, do they receive a notice of my rejecting their photos or them being deleted from my Sharing with them their pictures? Can get a bit touchy. Don't want to ruffle feathers

Yes, they use local storage.

On the iCloud website possibly, I've never tried to.

If you view them using Photos I believe that they do, are you referring to viewing them on the online iCloud photo library?

Yes, I know that article but if viewed in the Photos Library previews (presumably lower res) are created. It's a mystery to me.