Artificial turf is fully water permeable - it is the drainage that is of issue. The AT has to be lifted and drainage corrected with a slight slope away from any structures, the same as you would with a paved patio. A French drain may be required if the space is not large enough to allow for the correct degree of slope. A tree is not the answer.

There is an ongoing discussion on the pros and cons of AT. It is a plastic product and contributes to the increasing presence of microscopic plastic particles in our streams, waterways, rivers and oceans. It also adds to global warming, becoming very hot in sun, and tends to kill off soil microbiology. However, in small spaces it can be more efficient and less maintenance than a traditional turf grass lawn.

I think I need to get a professional in and probably with a JCB to resolve this issue. Likely a costly resolution sadly.

" However, in small spaces it can be more efficient and less maintenance than a traditional turf grass lawn." If your space is small, you can do a ground cover.

What is a ground cover?

Groundcovers are low growing, spreading plants that are used to....well, cover the ground! Many will often take a fair amount of foot traffic and so are sometimes used as a lawn substitute. Depending on your location, there are types of groundcovers that would be a viable alternative to a traditional turf grass or artificial lawn.

Check out this link: https://www.stepables.com 

Ahh thanks for clarifying. I would like to solve the problem though if at all possible. My daughter enjoys the grass in the summer doing cartwheels and playing etc

I'm confused about why the plastic grass is wet? It doesn't need to be watered.

I saw an article about some states seeking to ban artificial grass for homeowners. I believe California was mentioned.

You have to remove the artificial grass.

Forgot all about this thread. I haven’t been able to afford installing of proper drainage so opted to cover the grass during the winter which I find stops the water liking issuer and in turn halts black mould growth