10 Causes of Car Leaking Water & Solutions

Cars are expensive to maintain and especially fix, which is why it is best to know about a potential problem before the repair bill goes up any further than it must. One of the easiest things to notice and diagnose is water leaking from your vehicle.

The most common culprits of water leaking from a vehicle are the condensation from the air conditioner, and the buildup of water leaking from the cowl drain, both of which are normal occurrences that don’t require fixing.

If water is leaking inside the vehicle, then it usually involves defective weather stripping or sunroof seals, which can usually be purchased for $100 or less. Other problems include A/C drain and hose malfunctions and heater core issues, both repairs can cost almost $1000 for parts and labor.

This article explores possible reasons why your car might be leaking water and the solutions to those problems. We will go in-depth on when and what to fix and how much it might cost.

Is it normal for a car to leak water?

There are several perfectly normal reasons why your car is leaking water, including:

Condensation from the air conditioner

It is normal for the AC Condensate Drain to leak water if the AC has been running. Its function is to simply keep water from entering the cabin and will be located near the rear of the engine bay.

Cowl Drain

Liquid from your windshield wipers or rain will drain off the windshield and go into the cowl drain to direct water away from the cabin. This drain is typically located near the rear of the engine bay.

Is it normal for a car to leak water inside the vehicle?

It is not normal to have water leaking inside the vehicle. This is typically a sign of a leak in the equipment that seals the cabin, including sunroofs, windshields, door seals and weather stripping.

Find the source of the water to determine which part to replace. Seals and gaskets are easy to source and replace at a reasonable price for the average vehicle, but for the best price buy bulk weather stripping and cut it yourself.

A windshield replacement will be considerably more expensive to fix than door and window seals.

  • Bulk uncut weather stripping: $25
  • Custom cut weather stripping: $250
  • Sunroof Seals: $100
  • Windshield replacement: $200 – $400

Water Leaking Into Car When It Rains

Why is my car leaking water from the exhaust?

When water is leaking out of the exhaust of your vehicle, there is no need to worry.

Water leaking from the exhaust is simply caused by the condensation of gases from the hot engine cooling inside the tailpipe as it adjusts to the temperature outside.

The next time it is started, there is a potential for water to leak out of the tailpipe.

Leaks from the Engine (Why they happen & Potential fixes)

There are several reasons why a leak could be coming from the engine bay area, including problems in the engine cooling system or the windshield washer system.

Engine Cooling System

Leaking from the front of the engine can indicate a problem with the Engine Cooling System, which can cost between $250 – $500 for parts and labor depending on the vehicle model.

The function of the engine cooling system is to cool the temperature of the engine by pumping pressurized liquid through the radiator of the vehicle.

The highly pressurized nature of these heating and cooling cycles will deteriorate gaskets, seals, and hoses, potentially leading to a leak.

If you see liquid leaking from the front of the engine bay, then it is most likely coming from the radiator. Place a piece of white paper under the leak. If it has a color to it, typically green, then it is coolant coming from the engine cooling system.

It is very important that you get this properly diagnosed and fixed because it can lead to the engine overheating, which can cause irrefutable damage that could cost thousands to fix.

Leaking from the rear of the engine can indicate a problem in the Windshield Washing System, which is usually less than $200 to replace. But most of the time the culprits of water leaking from a vehicle are the condensation from the air conditioner, and the buildup of water leaking from the cowl drain, both of which are normal occurrences that don’t require fixing.

Overheated engines sometimes must be replaced instead of repaired due to the extent of the damage, which can cost upwards of $4000.

If caught early, engine cooling system repairs can be simple and inexpensive. The radiator, hoses, and gaskets can be easily accessed in most vehicles and do not cost much in labor to replace.

  • Radiators: $100 – $300
  • Radiator hoses and clamps: $50 – $150
  • Labor Costs: 1-2 hours at $100/hour average

Windshield Washing System

Made up of a reservoir, pump, hoses, and nozzles, the windshield washing system holds the liquid used to clean the windshield of vehicles. Since the system is unpressurized, the most common problem is simply a leak in the reservoir tank.

This is commonly caused by using water or other fluid with too high of a freezing point, leading to expanding ice cracking the reservoir in the winter months.

Replace the windshield washing reservoir to fix the problem, making sure to check that all the seals on the hoses and nozzles are properly in place.

  • Windshield washing reservoir: $30 – $100
  • Labor costs: ½ – 1 hour at $100/hour average

Leaks on Passenger Side (Why they happen & Potential fixes)

If water is leaking onto the passenger side floor, then there are a few reasons that it could be happening, including:

Clogged Drains or Loose Hoses

Some vehicles, especially those with sunroofs can experience water on the passenger side due to water backing up from an improper drainage system.

Instead of sending the water outside the car, it funnels it into the cabin. Check all the seals and replace if necessary.

Water on the passenger side floor can also come from clogged pipes and drains in the air conditioning system. This is the most common cause of leaks on the passenger side considering that these drains are typically installed very near to the passenger’s side floor.

  • A/C Hose and drain replacement parts and labor: $100 – $500
  • A/C System Compressor part and labor: $150 – $700
  • A/C Recharge: $125

Heater Core

If the passenger floor is wet and the liquid smells like coolant, then there could be a major problem with your heater core. Other signs that your heater core is failing include the car heater working poorly, and a low coolant level.

If not resolved the heater core tubes could continue leaking into the cabin through the firewall and dash, and eventually, the vehicle could start to overheat from coolant loss in the engine cooling system.

  • Heater core: $50 – $150
  • Labor: $400 – $800
  • Car detailing / Carpet cleaning: $150

Unfortunately, while the price for the heater core itself is typically reasonable, the labor to replace it is extensive.

There are numerous parts to remove and replace to reach the heater core, which makes the job time-consuming and expensive to pay for at a repair shop.

Leaks on Driver Side (Why they happen & Potential fixes)

If water is leaking into the driver’s side floor, then it could be caused by the same problems discussed above, only the problem is probably much worse.

If the liquid is caused by A/C or heater core malfunctions and the liquid has reached all the way over the driver’s side floor, then the drains could be extremely clogged, hoses could be disconnected near very delicate wiring, or the heater core could be severely malfunctioning.

The source of the water needs to be determined as soon as possible to minimize any potential repair costs.

Defective Window Equipment and Door Seals

If the liquid doesn’t smell like coolant, then the most likely culprit of water leaking on the driver’s side is rain coming in from defective window motors, regulators, or door seals.

As mentioned above, weather stripping and door seals are a cheap and easy fix, especially if you order it in bulk and cut it to the proper length yourself. Weatherstripping gets old, dried up, and cracked, and is one of the most likely causes of water leaking inside the cabin.

Window motors and regulators control the movement of the windows. If this system fails, it can cause the window not to close all the way and leak rain into the cabin.

These problems are best diagnosed by running water from a hose onto the vehicle and having someone sit inside watching for leaks. Once the leak location is determined, it is simple to replace the defective part.

  • Window motor: $50 – $400
  • Window regulator: $50 – $200
  • Labor: $130


Vehicles are important to maintaining because preventative maintenance and a quick diagnosis can save you thousands of dollars in repair costs.

Keeping an eye out for any leaking fluids will help to quickly determine if there is a potentially catastrophic problem with your vehicle. We hope we have helped you diagnose the water leaking from your vehicle and thank you for reading!