what to replace the septic tank cover with

Hi, I brake the lids of the septic tank. Impossible to find the same model at Homework, Homepro or Thaiwatsadu. I thought to use a thick tile or a rectangle concrete paving slabs for walking in the garden, but i can't find any big enough. I need 55 cm x 55 cm. I also thought about using a steel plate cut, but it's very expensive. Do you have any idea ?

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Have a look at Lazada. Cast iron covers are quite expensive, there are some cheaper, strong plastic covers that might fit.

If you can't locate a plastic lid, find a local carpenter or cabinet maker and have them cut one out of thick multi-core plywood. Coat it on all sides/edges with polyester or epoxy resin and you should get 5 years out of it.