Re-proofing waterproof

[Onze]

I had to wash my DD mac in a sac type jacket and waterproof trousers. Now they have lost the waterproof coating. I found a bottle of nicwax washing machine reproofing liquid in the local camping shop.
Has anyone used this product before? Is it worth it? I would rather make do and mend, but do not want to waste money.
Any thoughts?
Thank you

Check the instructions on the waterproof, but should work. Nikwax also make a "Techwash" for washing waterproofs without losing the coating. As long as you don't wash in detergent you should be able to go several washes before reproofing again

Or you can just wash in plain water and tumble dry (check care instructions).