Do Evap Lines Disappear? Meaning, Causes, and What To Do

It can be difficult to interpret a pregnancy test when evaporation lines are present. These lines should not be confused with a positive pregnancy result, but they may cause confusion for some individuals.

They are usually just an indicator that the test was left sitting too long past the recommended reading window and the urine evaporated, leaving a line.

Do evaporation lines disappear? No, an evaporation line won’t disappear. Once enough urine has evaporated to leave a line, the evaporation line is there to stay. This is why some people get confused and assume a lasting line means they are pregnant. If it’s an evaporation line, that is not what it actually means.

In the following, you’ll learn how to identify an evaporation line so you can accurately read your pregnancy test and feel sure about the results.

Evaporation Lines on Pregnancy Test

It’s important to follow all of the directions when you take a pregnancy test so you don’t get confused by evaporation lines.

What Is an Evaporation Line on a Pregnancy Test?

An evaporation line is a line that appears within the testing window as the urine from the test evaporates.

Since this line appears where a positive pregnancy test line would, many people confuse the two. However, an evaporation line is not a sign of pregnancy.

What Causes an Evaporation Line?

Urine starts to evaporate after a while, and that’s why you should read your test results within the time window assigned.

The evaporating urine will eventually leave a shadow of a line that can be misleading, so you should not read a test after the time window expires.

Evaporation Line vs. Faint Positive

An evaporation line appears when urine evaporates in the pregnancy test window. These lines tend to be colorless and can appear as almost shadows of an actual line.

You tend to see evap lines when you try to read a pregnancy test after the time window has passed.

A faint positive will appear within the allotted testing time, and it will have color. You may see a very light pink or blue line, but an actual faint positive will offer some color to help you distinguish it from an evaporation line.

A faint positive will also be a thicker line than an evaporation line.

What Color Are Evaporation Lines on Pregnancy Test?

An evaporation line is usually gray, sort of like a shadow of an actual line.

Do Evaporation Lines Get Darker as They Dry?

Your evaporation lines will probably not get darker as it dries. Though it is possible, it’s unlikely.

Do Evaporation Lines Go Away?

Evaporation lines don’t go away. Once you see one, it’s likely there to stay. That does not mean that the test is giving you a positive test result.

Do Evaporation Lines Disappear With Water?

Evaporation lines will not disappear if you pour water on the pregnancy test. You will also compromise the test results by adding water, so it’s not recommended.

Is a Faint Line Still a Positive Pregnancy Test?

A faint pregnancy test line is still a positive pregnancy test, assuming it’s not an evaporation line. A positive pregnancy test line will be the color assigned by the test, usually blue or pink.

Even a light-colored line means you are pregnant. However, a gray evaporation line does not indicate pregnancy.

A young woman sitting on the couch holding a pregnancy test and appearing confused about the results.

What Causes Faint Line on Pregnancy Test?

A faint line on a pregnancy test can be caused by many things. Your hCG hormones may still be low if it’s early in your pregnancy, and that can lead to a light line.

If you take a pregnancy test with urine that has been diluted by water you’ve been drinking that day, you may also get a light line. That’s why it’s recommended that you take a pregnancy test with the first morning’s urine.

Evaporation LineFaint Positive Line
ColorGray or shadowPink or blue
Line ThicknessThinner Normal thickness
Time To AppearAfter allotted time windowDuring allotted time window
Line ClarityFuzzy or lightClear, even if light
Behavior Over TimeAppears after test time has passedStays on the test 

How Common Are Evaporation Lines?

Evaporation lines are fairly common and are a great reason to follow the directions on your pregnancy test. Read your results within the recommended time frame, and you likely won’t have to worry about evaporation lines.

What To Do if You Suspect an Evaporation Line

If you think you might be looking at an evaporation line instead of a faint positive, retest. Get a new test, follow the directions, and read it within the testing window time. This will help ensure you get a reliable result.

How To Avoid Evaporation Lines on Pregnancy Test

To avoid evaporation lines on pregnancy tests, follow the directions, and don’t read the test after the time recommended. Throw away a test after the time to read it has passed.

Adding Water to Evaporation Line on Pregnancy Test

Adding water to an evaporation line will not change the result or give you a better chance of getting an accurate result. 

Evap Line Turned Out To Be Positive

It is possible for your evaporation line to end up actually being a faint positive line, especially if you take a blue dye test.

The blue dye tests are more likely to mimic the color of a gray evaporation line, and this can make initial results confusing.

Related Questions: 

Why Are Blue Dye Pregnancy Tests Bad?

Blue dye tests can make telling the difference between an evaporation line and a faint positive even harder.

Because your evaporation line may be light gray, it’s easy to confuse it with a light blue faint positive test. Pink dye tests can help you avoid this confusion.

What Happens if You Wait Too Long To Check Pregnancy Test?

If you wait too long to check a pregnancy test, you may mistake an evaporation line for a faint positive.

This can be devastating because you will think you are pregnant only to find out you simply read the test too late and were looking at the wrong type of line.

Do Pregnancy Test Results Disappear?

Generally, pregnancy test results won’t disappear on a test. If the test shows positive, it will stay positive. If you retest days later and don’t see a positive test result, call your doctor.

Closing Thoughts

Follow the directions when you take a pregnancy test to increase your chances of getting an accurate result.

Now that you know what evaporation lines are and what causes them, you can avoid any misinterpretation the next time you test.