The owner claims that they were unaware of the irrigation system and therefore not liable for the damage.
Liability usually needs negligence to establish it.
So was the lot owner negligent? Perhaps. Or perhaps the landscaper was negligent in which case the landscaper might be liable.
Either way, hopefully insurance, either the strata’s or the lot owner’s or the landscaper’s, will cover any damage.
If it’s covered by strata insurance that might be the first to try?