As I have no idea as to CA or Los Angeles's laws on utility sub-billing, I have no comment as to the legality of what the landlord is doing.
Utilities and charging for the services are often very heavily regulated. Your state or city may have laws that prohibit landlords from charging tenants for utilities unless each tenant has separate meters or services or from using other companies to bill you.
However, as someone who pays utilities charges every month, I can only wish that I am paying "$24 for water, $24 for Sewer, and $8.50 for trash". The amounts for water and sewer are very low compared to what I am paying. Of course, the amount charged is usually related to how much is used. Perhaps if you live by yourself and are hardly ever home and do not use the water much, $24 may be too high.
My understanding is that many areas of CA are having severe water restrictions. Perhaps the increase in charges is related to the restrictions.
Have you talked with the landlord to find out why the charges have been increased?
First, you should read the lease to find out what your obligations are. If your unit is separately metered, you can easily check the accuracy of the NWP bills. If your unit is not separately metered, the lease probably describes how the landlord will calculate your share of utilities. In that case, you should check the calculations. If the allocation criteria is square feet, you should ask to see the records of the square feet of the other units and add them up to make sure that NWP is including in the calculations all square feet in the total project. If they calculations include all of the utilities of the project, including the management office, and the square feet total doesn't include the management office, then all tenants will be paying a share of the utilities of the managment office. That would be a proper charge only if the lease says so. That would be a common way to do things in a commercial unit under a net-net-net lease. That method would not be common in a residential setting, but would be legal. So the starting point has to be the lease.
If your unit is not separately metered and the landlord won't cooperate by showing you the records of utility costs and square feet, that's suspicious. If that happens, consult an attorney about a lawsuit on behalf of all past and present tenants.
This answer must not be relied on as legal advice for the reasons posted here: http://davidphipps.com/docs/Disclaimer.doc . And I am not your attorney.