If your bill is very high check to see if there is a "utility tap." It is possible the bill does not reflect what you use. A utility tap means someone uses your utilities without permission. They could be using electrical, water, or gas. They could be using utility line/pipe/wire to get service. Utility taps may happen in various ways. For example, your neighbor’s unit is hooked into your meter. So, you end up paying for lighting in a common area. Or hot water for the entire building is on your gas bill.

If you suspect that there is a utility tap, you should contact your landlord. Under Illinois law, landlords must inform a tenant if they are responsible for any common area service. This includes paying for other units. Without notice, the landlord is responsible for compensating the tenant. The landlord must remove the tap.

Utility companies must ensure that your utilities are not stolen. You can ask the utility company to investigate. This must be within 30 days after you receive the bill. After inspecting the meter, they should issue a report. This will determine the presence of the utility tap. The report should indicate if the landlord benefits from the usage of the utility service. Make sure you save this report. You can contact the Illinois Commerce Commission (ICC). You can call them at (800) 524-0795. Do this if the utility company does not inspect the claim.

Once the utility company determines a utility tap exists, you should send the landlord a written notice. State you are paying for additional utilities. If your landlord is willing to work something out, proceed with negotiations. If your landlord does not respond to your notice, send a letter to the utility company. In this letter you should state that you will not be subject for extra charges.

The utility company may charge the customer receiving service from the illegal tap. The utility company must prove that:

• Tampering has occurred with the utility's wires, pipes, meters, or other service equipment,
• The customer has benefited from the tampering, and 
• The utility's billing is reasonable.

If the utility company fails to take action, you should file a complaint with the ICC regarding over-billing.